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11 Jul 2008

DYAR Mailbag

by Aaron Schatz

When we announced the new version of our individual stats on Monday, it spawned a lot of discussion among Football Outsiders readers. Some people thought we had sold out. A few readers were worried that changing our nomenclature to yardage was a sign that we no longer were measuring performance based on situation and opponent. Others liked the new numbers and their names, filled with piratey goodness.

I'm not surprised there was a lot of discussion, because it took a lot of discussion to get to this point. Believe it or not, the change from DPAR to DYAR has been in the works for almost two years. These new statistics were bandied about on the Football Outsiders staff e-mail list numerous times. There was an ad hoc focus group that gave their thoughts on how we could best improve the accessibility of our stats. Instead of seeking advice from hardcore readers, I went to people who deal with the same issue of trying to explain complicated concepts to a wide audience -- other Internet sportswriters, guys like Joe Sheehan and Roland Beech and King Kaufman. Everybody had different ideas. We threw around the idea of putting everything on a 0 to 100 scale, but that's something you do with a rate stat, not a total stat. We played around with a "tweaked" DYAR that always looked exactly like actual yardage, with the best passing games worth roughly 400 yards. However, if you make replacement level zero yards, you have to make "average" something more than zero yards, and that leaves you with guys getting 160 DYAR on three pass attempts. Try adding that up for season totals and you get a total mess.

The reader discussion on the original post from Monday ended up somewhere around 200 comments, with people disagreeing with each other about how our stats are computed, what they mean, and what they should be named. If that's not a good example of how difficult it is to give an advanced football metric a name and form that everybody can agree on, I don't know what is.

Of course, it didn't help things that one of the new stats we introduced, "Equivalent Yards (EqYds)," didn't seem to actually show what we wanted it to show.

The idea behind "Equivalent Yards (EqYds)" was to create a simple number that an average fan could compare to standard yardage in order to see if a player was more or less valuable than his stats otherwise would indicate. Unfortunately, it turned out that "players with DVOA above 0% will have more Equivalent Yards (EqYds) than actual yards" was not true, and we were ending up with strange things like Adrian Peterson's 2007 season, with 1,344 rushing yards but only 1,060 "Equivalent Yards (EqYds)."

The reason is pretty simple. The original Equivalent Yards (EqYds) was just "success points" adjusted to look like yards. We wouldn't list guys by just success points without looking for opportunity, so thinking this was going to work was pretty darn stupid on my part.

The good news is that I went back to the drawing board, and it didn't take me long to come up with a newer version of Equivalent Yards (EqYds) that does what we want: provides a simple way to see if a player's performance was better or worse than his actual yardage total in that game or that season.

Our new version of Equivalent Yards (EqYds) is based on DVOA compared to league-average yardage. For example, the average running back over the past few years has gained 4.16 yards per carry, and Adrian Peterson's DVOA of 16.4% ends up as 4.85 yards per carry. Then, the new formula adjusts for the baseline on each play, so that guys who succeed in a situation with a low baseline (say, a first down on third-and-25) don't end up with 300 "true yards."

This means that the statement "players with DVOA above 0% will have more Equivalent Yards (EqYds) than actual yards" is still not correct. However, we do end up where players with DVOA above 0% will have Equivalent Yards (EqYds) per attempt over the league average of yards per attempt. That makes a lot of sense. The standard for a strong passing day stays 300 yards, for example, but now Football Outsiders readers are looking for 300 Equivalent Yards (EqYds), not 300 passing yards. When Jon Kitna throws the ball 50 times and ends up only completing half his passes, with 350 yards and three interceptions, he won't have 300 Equivalent Yards (EqYds). That's not a 300-yard game that really has the value we tend to associate with 300-yard games.

Here are a couple examples of how the new method works. I'm going to use examples from single games, rather than full seasons, because that's what Equivalent Yards (EqYds) are really designed to help readers understand. Here are eight quarterback games from last year that had roughly 250 standard passing yards. I think the new Equivalent Yards (EqYds) stats does a good job of showing which players really had good passing days and which players did not.

Player Wk Opp Comp Att Yds TD INT Sacks True
18-P.Manning 14 BAL 13 17 249 4 0 0 395 204.9% 228
17-P.Rivers 12 BAL 25 35 249 3 0 0 385 50.7% 145
8-C.Redman 17 SEA 17 27 251 4 0 2 369 91.7% 172
10-E.Manning 17 NE 22 32 251 4 1 1 368 51.9% 140
5-D.McNabb 10 WAS 20 28 251 4 0 2 352 44.4% 125
8-M.Hasselbeck 12 STL 21 38 249 1 1 5 204 -13.5% -6
3-D.Anderson 16 CIN 29 48 251 2 4 1 109 -46.7% -121
7-T.Jackson 15 CHI 18 29 249 0 3 2 87 -35.7% -45

Here's another example, the top running backs from Week 9, the week Peterson broke the all-time rushing record. I'll run both the new and old versions of Equivalent Yards (EqYds), with the nine players who had 100 rushing yards and two others who are particularly interesting.

Player Opp Att Yd TD FUM True
"Old" True
28-A.Peterson SD 30 296 3 1 253 203 91
26-C.Portis NYJ 36 196 1 0 191 175 38
23-M.Lynch CIN 29 153 1 0 156 143 32
34-E.Graham ARI 34 124 1 0 140 139 14
36-R.Dayne OAK 21 122 1 0 113 105 21
29-J.Addai NE 26 112 0 0 101 99 11
25-J.Fargas HOU 23 104 1 0 152 135 37
25-L.White CAR 31 103 1 1 110 115 3
28-W.Dunn SF 27 100 1 0 96 101 2
24-M.Robinson ATL 17 67 0 1 20 42 -28
36-B.Westbrook DAL 16 65 1 0 120 104 33

Note that Peterson still has fewer Equivalent Yards (EqYds) than actual yards in Week 9 -- because as good as he was, he wasn't 9.87 yards per carry good. He was stuffed on some third downs, lost yardage on three carries, and fumbled the ball once. That's not to say that this game was poor by any means. Peterson's totals of 253 Equivalent Yards (EqYds) and 91 DYAR still end up as the best of the year by a significant margin, and one of the top games of all-time.

Meanwhile, Robinson and Westbrook give a great example of how two games with similar yardage can be very different. Westbrook had a 63 percent Success Rate on the day against a good run defense, never losing yardage on a carry. Robinson had a 41 percent Success Rate against a poor run defense, with a fumble and four different carries that lost yardage.

Justin Fargas might give us the best example here of where Equivalent Yards (EqYds) can be useful. Fargas had a very consistent day, with nine carries between six and 11 yards. He had seven first downs and a touchdown, converting four out of five runs with 1-2 yards to go. Because he didn't have any really long runs, his total for the day was just 104 yards. 23 carries for 104 yards sounds like a pretty good day, but not a great one. 23 carries for 152 Equivalent Yards (EqYds) gives you a better idea of how valuable he really was to his team.

Hopefully, this new method for computing Equivalent Yards (EqYds) answers a lot of questions. (For example, the best tight ends no longer all have fewer Equivalent Yards (EqYds) than actual yards.) Now let's see if I can answer some of the other questions. These are all from the discussion thread on that Monday article.

Joe T.: So a red zone fullback would have his DPAR skewed in one direction, and his DYAR skewed in the other?

This question was one of many comments that seemed to misunderstand what we were doing by changing from "Defense-adjusted Points Above Replacement" to "Defense-adjusted Yards Above Replacement." The value of an actual yard didn't change. All our stats are still based on computing success towards both a first down and a touchdown, and comparing that success to a league-average baseline based on situation and opponent.

I should point out that the "success points" system is not actually based on finding out how often teams score from every specific down-and-distance at every time in the game, or anything like that. To be honest, it isn't quite that complex or exact. Reader Scott C. wrote:

Football Outsiders statistics start out by finding the value of plays, in points. It does this by looking at the down/distance/situation before and after a play:

How many points does a drive attain on average at first down and 10 from midfield?
How many points does a drive attain on average on second down and 5 from the opponent's 45?

These two point values differ slightly. That first down play for 5 yards in between those two points is worth a value in POINTS that is the difference between the values above. Thus, any play can be tied to expected value point differential. This needs further adjustments, but as far as I can tell, is the foundation of the statistics at FO.

Actually, Scott, it isn't the foundation of the statistics at FO. The "success points" system is just taken from The New Hidden Game of Football and then gradually tweaked over five years through trial and error to be as accurate as possible. It isn't as strict as the kind of system you describe, but it does its job.

Alex: Why can't we keep DPAR and bring in DYAR? What, is DPAR going to get jealous?

Once again, this comes down to accessibility to the general public. There's no reason to have two statistics that measure the exact same thing in almost the exact same way. That's confusing.

However, I have to admit that DPAR and DYAR are not quite exactly the same. In a quick note in the original Monday discussion thread, I said that changing from DPAR to DYAR was no different from changing the temperature scale from Fahrenheit to Celsius. I apologize, because after thinking further, I realized two things that changed with DYAR.

First, the new, improved version of DYAR is more accurate, because it accounts for the fact that the average situation faced by one player may be harder than the average situation faced by another player. The old method took total success points, subtracted the baseline on that play (or those plays), and then multiplied by a coefficient to get DPAR. The new method takes total success points and multiplies by a coefficient, and then subtracts the baseline multiplied by a slightly different coefficient in order to get DYAR. Therefore, the ratio between DPAR and DYAR will be different on each play. Those differences get smaller if you add the plays up into games, and even smaller if you add the games up into seasons, but they are still there.

Second, the translation of "success points" into yardage didn't end up with the same coefficients for every position. For an explanation, let's look at short-yardage situations. Last year, the average pass attempt on third-and-1 or fourth-and-1 gained 5.4 yards and was worth 1.5 "success points" according to the basic system at the foundation of DVOA and DYAR. The average running back carry on third-and-1 or fourth-and-1 gained 3.2 yards...  but was worth 1.6 "success points." How on earth can passes gain more yardage and lead to less success? Because, "success points" are not based simply on gaining yards. They are an attempt to balance yardage with progress towards a first down, and the big successful event here is the first-down conversion -- which is more frequent on a run -- rather than the yardage.

That means that even if you ignore the small differences in the ratio of DPAR to DYAR caused by the improved accuracy of the new method, there are still larger differences in the ratio from position to position. Perhaps the better way to create DYAR would have been to come up with a universal translation from "success points" to yardage based on team totals, rather than figuring the equations separately for each position. I'm certainly willing to look into the possibility of making that change next offseason, but there really isn't the time to do the work now. (Even just re-doing Equivalent Yards (EqYds) put me behind on a lot of business things I needed to deal with this week.)

Patrick: Are we now double counting? In the olden days, the DPAR for a completed pass were divided between the QB and receiver, right?

No, DPAR have never been split between a quarterback and the receiver. It counts for both. We would like to one day be able to make such a split, but we have not done enough research. This is also one of the reasons why, although I do it in Quick Reads, I am hesitant to add together values in rushing and receiving (or for quarterbacks, passing and rushing) to get some sort of "total value." We don't know if a yard of DYAR rushing is equal to a yard of DYAR receiving, so we can't say that a player with 50 rushing DYAR and 20 receiving DYAR is equal to a player with 20 rushing DYAR and 50 receiving DYAR.

Which brings us to another question from Patrick:

Patrick: With DPAR (or VORP), you could take a replacement offense (maybe 150 points? ‘06 raiders?), then add up all the DPAR from individual players and it would give you a ‘predicted points scored'. With DYAR, can I take a replacement team yardage (4000-yard season maybe?) and add all the individual DYAR totals and get a predicted yardage? will their be a table for how many points a team with a given teamwide True Yardage would be predicted to score?

Actually, we never really meant for it to work this way, for a number of reasons. First, you couldn't add together everyone's DPAR because passing yards counted for both quarterbacks and receivers -- but you couldn't just use half of the quarterback's DPAR and half of the receiver's DPAR, because receiver DPAR didn't account for interceptions. You also had to deal with the fact that field position is fluid. That means that to approximate how well a team played compared to its DPAR stats, you would also have to consider the DPAR stats of all the offensive players who faced their defense -- except you would have to re-do DPAR so that "replacement level" represented more offense, not less offense, since a replacement-level defense would allow more points.

LearnFromTheMasters: Funny that Baseball Prospectus is mentioned in this article. While they provide stats like EQA and QERA (which are on the same scale as batting average and ERA, respectively), the stats they use for overall player comparisons are from the VORP/WARP category — expressed in runs ("points") and wins ("tens of points").

At least this guy mentioned EqA. Another reader wrote "[DYAR] is tantamount to baseball sabermatricians moving from a runs-based system to adjusted batting average just because old-school fans love BA." Apparently, he didn't know that Baseball Prospectus does precisely this. That's what Equivalent Average (EqA) is meant to be, "adjusted batting average." It measures all offense, not just hits per at bats, but it does it on a scale the average person understands, where .300 is good and .200 is bad.

Baseball Prospectus expresses things in terms of runs because that's how baseball people think. Players are listed with runs scored and runs batted in. How many points does a star football player generally create in a good season? Who knows? How many runs does a star baseball player generally create in a good season? Everybody knows the answer: 100. When I asked BP guys about changing our individual statistics to yards, they were surprised I didn't do that in the first place. Let's be honest -- a lot of people are attached to DPAR because that's what we have been doing for five years. If I had put this all in terms of yards back in 2003, it wouldn't have been very controversial.

As for putting things in terms of wins, the baseball people have been doing research far longer than we have, and they have ten times as many games to work with each season, so they have a much better model of how runs translate into wins. It also helps that the model can be simplified to "ten runs is roughly one win." Would it be as easy to understand if 23.6 runs was roughly one win? Maybe if you live in a society where everyone is born with 23.6 fingers and the language uses a base-23.6 number system or something.

Goo: Isn't the whole point to move beyond yards and think about what actually helps teams win games? You don't win by getting more yards than the opponent, you win by scoring more points, and that was one of the big appeals of DPAR... At least with DPAR I could subtract it from a team's point total or swap players and use the old pythagorean formula to run “what ifs” with different players; how do you do that with DYAR?

This is the other problem with creating some sort of "wins over replacement" statistic. Baseball stats, as we all know, are much less dependent upon teammates than football stats are, plus there's no crossover between offense and defense. When Brian Urlacher intercepts a pass, Rex Grossman may get to start a drive already in field goal position, but Justin Upton does not get to start on second base if Brandon Webb strikes out the side. While game situation may slightly affect pitch selection, for the most part a Manny Ramirez home run has nothing to do with who is on deck or who is on first base. That's why baseball people can determine very specific values for each player, switch out one player for another and approximate how many wins it would add, run models that work out "contract dollars per win produced," and so forth. Football just doesn't work that way -- not yet, anyway. You can't take Randy Moss's stats from New England, stick them in Oakland's offense instead of Johnnie Lee Higgins, and say "this is how many points Oakland would have scored if they had not traded Moss." 

This is all sort of wrapped up with a general problem that we have. To but it bluntly, there is a portion of the readership which seems to believe that our stats are more accurate than they really are, and they often try to use those stats to do things they weren't really meant to do. DYAR will give you a more accurate picture of how good players are when compared to players at the same position, and that's the goal of the individual statistics. We don't mean for people to use the individual stats to build team models.

Thok: Shouldn't it be Yards Adjusted for Replacement and Defense, a.k.a. YARD?

Yes, that exact name came up when we were figuring out what to call this stuff. Close your eyes and imagine that you are listening to me on the radio. Now you should understand why it can't be called "YARDs."

I understand the people who don't like the name "Equivalent Yards (EqYds)." Originally, my plan was to call them "Equivalent Yards," just like BP calls its stat "Equivalent Average." Then someone suggested "Equivalent Yards (EqYds)," and that name sounds so much simpler. But I'm willing to entertain suggestions on name changes before the season begins and we start putting this out there in Quick Reads (which will be moving from FOXSports.com to ESPN.com). Do people like "Equivalent Yards" better? I would rather something that is a name than something that is yet another acronym in our alphabet soup.

Ammek: Now that you are working from five years of data (2003-07), I wonder: has the value of Average in DVOA changed at all? If, to take an extreme scenario, passing success on first down increased by, say, 15 per cent in 2008, would DVOA adapt to that? Or does Average mean ‘average for the era'?

Right now, all DVOA stats are done based on the same average baselines, which are based on 2002-2006 (team) and 2003-2007 (individual). (At a certain point, there are only so many plays I can fit in a spreadsheet, and it slowed things down too much to use 2002 in the individual baselines.) You are correct that this may create problems because the offensive environment and style of the league change over time. Separate baselines for each year are impossible, really, but eventually we may need to look into some sort of normalization process. I've thought about trying some sort of "rolling baselines" that change for each year based on the years before and after. However, what's interesting is that while there are small changes up and down each year, the DVOA Era can really be split into four parts based on major jumps in the offensive level: 1995, 1996-1999, 2000-2001, and 2002-2007. There was a huge drop in the offensive level in 1996, a jump in 2000, and another jump in 2002. Yes, 2004 was a little higher, 2005 a little lower, but in general, offensive level from 2002-2007 has been pretty steady.

Gat: Are kickers going to be ranked using DYAR instead of DPAR? That seems… stupid.

Actually, kickers have never been ranked using DPAR. The special teams stats are all based on scoring value compared to average, not replacement level. In addition, the methods for turning kickoffs and punts into an approximate number of points are much more accurate than the methods for turning rushing and passing into an approximate number of points, because we only have to worry about the value of field position, not the value of earning a new set of downs.

Chris: A lot of individual stats are dependant on the venue as a huge variable which doesn't effect either say the QB or the defense. Playing in a snowy windy game in Buffalo with 5 degree temps will hurt both QB's stats and help both secondaries.

This comment gets to the other thing I was supposed to fix this offseason. We talked a lot last year about adjusting DVOA for the weather, because passing games were making defenses look better than they really are and making quarterbacks look worse. You may be wondering what happened to this project. Well, I spent a ton of time on it in February and March. I looked the last few years of DVOA based on the weather in each game, both the wind speed and the precipitation. Here's what I found:

  • Wind speed did seem to affect passing stats, with players doing better indoors, and gradually getting worse as wind speed picked up, starting around ten miles per hour.
  • The effect of precipitation varied widely from year to year. Some years, rain games and snow games actually had higher offensive DVOA than games indoors. Once you corrected for wind speed, the effect of precipitation seemed to be just statistical noise, with no pattern at all.
  • There is no standardization of how teams mark the weather for their games, putting us in situations where we had to estimate wind speed or go back into past weather data online to find temperature. This would lead to problems correcting past seasons for weather effects.

But most importantly...

  • When I tried to add wind adjustments to DVOA, it actually lowered the predictive value of the stats, as well as the correlation from year to year and from Weeks 1-9 to Weeks 10-17. Frankly, that makes no sense. Theoretically, adjusting for bad weather should improve year-to-year correlation, and it should especially improve correlation from the first two months to the last two months, making up for the fact that wind makes passing harder in November and December for teams that play outdoors in the north.

With those kind of unclear results, I was simply uncomfortable adding the adjustment to all our stats. I don't want to make changes unless I feel confident they are improving things. So for now, we'll continue to note when bad weather may have affected DVOA, and we'll continue to hope that readers continue to read our stats through the filter of common sense, and we'll try to play with this again next spring.

Finally, a couple of questions about specific players.

Steelberger: Personally, as a Steelers fan, I find any system that ranks Sage Rosenfels ahead of Ben Roethlisberger (new DVOA) sort of ridiculous.

The reason is primarily opponent adjustments. Rosenfels went through the Gauntlet of Hell last year, with two games against the top pass defense in DVOA (TEN) as well as games against the pass defenses ranked second (SD), third (IND), fourth (TB), and eighth (JAC). He didn't play a game against a pass defense ranked below 19th.

Disco Dack: Quinn Gray is now top 10 in DVOA?

Yes, I know, that seems strange to me too. A lot of that comes from that meaningless final game against the Texans, but still, believe it or not, Gray has a positive DVOA in every single game from 2007 except one. That one, of course, was the Monday Night Football against Indianapolis when he replaced an injured David Garrard and couldn't hit the broad side of a barn. Let's be honest, for most of us, that's about all the Quinn Gray we really saw last year so all we remember is how bad he was in that one game.

Of course, just because Quinn Gray is in the top 10 in DVOA doesn't mean he was one of the top 10 quarterbacks in the league last year. You have to consider sample size. You have to consider how good the Jacksonville offense was around him. A nice DVOA in 155 attempts doesn't mean you have the stuff to be a starting quarterback in the National Football League. We call this the "Doug Johnson Effect."

With this now out of the way, early next week I'll get to the article on the best and worst quarterback seasons and games since 1995.

Posted by: Aaron Schatz on 11 Jul 2008

107 comments, Last at 29 Jul 2008, 6:20pm by Jim Glass


by anotherpatsfan (not verified) :: Fri, 07/11/2008 - 6:53pm

Thanks Aaron.

Settling back with popcorn to watch the carnage...

by MJK (not verified) :: Fri, 07/11/2008 - 7:39pm

Thanks for all the clarification, Aaron.

A couple of things:

First, on the name. Has the name "Effective Yards" been discusses (or is it already in use somewhere). I like that much better than "Equivalent Yards", because what you're really measuring is how effective the player was. "Equivalent" begs the question "Equivalent to what", and while you seem to have a good answer to that, your answer requires a fair bit of complex explanation that you probably don't want to go into with the average FOX-Sports fan (or ESPN reader, if you're changing). "True Yards" has a nice ring to it, but it sounds, on first hearing, a little, um, pretentious to me.

Regarding the weather: Two thoughts on why weather might make DVOA less predictive.

First, how did you try to do the adjustment--as a linear shift? The effect might be nonlinear. A 20 mph wind may reduce a +50% passing DVOA team (in a dome) to a +15% team, but a +10% team to just a +2%. I imagine trying to glean enough data that's sufficiently accurate (given only about 1/3 of teams play in an open stadium, and more than half of those games probably have nice weather) to derive what the nonlinearity is would be really, really hard.

Secondly, am I right in my understanding that a team's total DVOA is a function of their DVOA in different types of plays, weighted according to how often they use that type of play? Or that they are weaighted according to league averages? In either case, DVOA doesn't know that a coach is smart enough to change up his playcalling depending on the weather.

For example, suppose you have an offense led by QB Frosty McBlowhard that plays in high winds for five out of six games. It runs about 70% of the time because of the adverse passing conditions, and has a running DVOA of say +5% and a passing DVOA also of +5% (let's make the math easy), so their total DVOA, non-weather adjusted, is +5%. If we weather adjust, we can say in calm air we might expect their passing DVOA to be +15%, but that will only slightly raise their total weather-adjusted DVOA, because they only pass 30% of the time. Of course, in calm air they're likely to pass a lot more, but DVOA doesn't know that. So weather-adjusting DVOA will UNDER-predict the goodness of an offense unless it can somehow also predict a shift in playcalling.

On the other hand, consider a dome team with an offense led by QB Archer Trueball, with a pass DVOA of +50%. The have a pretty good running game with Homer von Shiftylegs (+15% DVOA), even after running back Bam Crushchest left for the year with a freak injury, but because they're now thin at RB, and their pass offense is so good, they pass 90% of the time. Now imagine that they have to go play Frosty's team during Hurricane Xena. Weather adjusted DVOA says their pass game will drop to +5% DVOA, so obviously they're going to run more, but DVOA doesn't know this. Hence weather-adjusting will, again, underestimate their offense. On the other hand, you can also imagine a team with a bad running game where weather-adjusting could over-estimate their skill.

by MJK (not verified) :: Fri, 07/11/2008 - 7:43pm

Sorry for the long post, but one other comment about weather.

It doesn't surprise me that non-wind conditions have an unpredictable effect on the passing game. I've heard a number of QB's say in interviews (including Tom Brady) that they like slippery conditions, because it slows the pass rush down and gives them more time to throw. And if footing is bad for WR's running their routes, it's worse for DB's who don't know what the routes are and have to make sudden and unexpected breaks and turns when reacting to WR's. On the other hand, QB's that rely on their mobility to protect them are going to have issues in bad conditions. Also, conditions could prompt a speed rushing team to replace its rushers with bigger DT's, and maybe do better than they otherwise would have because they catch the other team's O-line off guard.

I would actually expect precipitaiton would affect the running game more than the passing game, because it would make cutbacks harder and fumbles more likely. Did you just look at weather effects on passing stats, or did you look at the running game, too?

by Chris (not verified) :: Fri, 07/11/2008 - 7:46pm

Thank you for addressing my comment. Gamblers know that strong winds are the easiest way to reduce scoring. It makes passing and deep passing exponentially more difficult and the 11 man defense ends up having to cover less space making it harder to score.

It isn't just the weather though, but the actual field. The flatter the surface the faster the game. Playing in thicker grass will slow down the game as everybody is slower. It might not necessarily equal more points, but it will be a faster game.

In general games indoors on flat surfaces favor the passing attack, and snow games can result in high scoring because it is harder to play pass defense on snow because the Receivers know where they are going where as the DB's must react ( and even slower than usual when you don't have very good footing).

I would like to see if there is correlation between precipitation a( rain or snow) and aggressive/conservative coaches and point totals. I would think the conservative Joe Gibbs type would change game plan which leads to lower scoring ( not the weather), where as more aggressive play callers might try and attack a defense on weak footing. The variable that effects the change isn't the weather but the coaches and their perception of the weather and style.

Giants fans were complaining about the horrid conditions Eli and the Passing game had to play in at the end of last year (Buffalo and Washington games especially) and even the London game on the Pitch. I am not saying Eli was fantastic or even average but there was a need for a variable to take into account the horrible conditions. His stats would have been better if he were playing in say Sunny Arizona on fake grass.

So basically we can all see with our eyes that playing in cold, windy, snow flurry December is easier for the defense and harder for the passing game but you guys haven't figured out to incorporate it yet so it isn't reflected in DVOA?

Making a "True" DVOA would be incredibly difficult but I believe this variable is too big to leave out. Thanks for your work guys.

by mikeabbott (not verified) :: Fri, 07/11/2008 - 7:48pm

I vote for calling them METERS
(acronym to follow)
just for radio

by John (not verified) :: Fri, 07/11/2008 - 9:53pm

Great posts, thanks a lot. I really like MJK's "Effective Yards" suggestion...rolls off the tongue much better, and doesn't evoke any "comparison" thoughts, for lack of a better word. I'd be fine with "True Yards" as well, but I agree with MJK on that count also.

by Temo (not verified) :: Fri, 07/11/2008 - 11:46pm

Great job on the post Aaron, it really cleared up a lot of things. Although seeing as how your job is, after all, at least related to exhaustive statistical modeling, it's somewhat alarming that you still use excel spreadsheets for your main calculations. :)

MJK, I think you may be misunderstanding how total DVOA is calculated, though I'll let someone else answer for I'm not entirely too sure myself.

by Goo (not verified) :: Sat, 07/12/2008 - 12:14am

Thanks for clearing things up, Aaron. While I'd still prefer things to be measured in scoreboard points, I can understand the reasons for the change, and I even see the advantages of using DYAR over the old DPAR. Here's to a fruitful first season with the new stats...

by Bobman (not verified) :: Sat, 07/12/2008 - 1:04am

I like Equivalent Yards--It sounds more "engineered/manufactured" and less likely to be misunderstood by casual fans as an actual 36-inch measurement. It is a mumbly mouthful, to be sure and true yards is a speech-writer's dream. But potentially confusing. And if we're trying to make things clear (i.e. avoiding YARD), Eq Yards seems clearer to me.

Not very piratical, however.... Maybe Scurvy Dog Equivalent Yards is better, but I'll leave that to Bucs fans and Pastafarians to hash out.

by Bobman (not verified) :: Sat, 07/12/2008 - 1:12am

or Effective Yards, though that might be considered confusing as well. To me, Equiv Yards says "we're trying to line all these things up and see how they stack up against one another--are they equivalent or not." If X had 110 Equiv Yards and Y had 110 Equiv Yards, regardless of their raw stats, they had equiv games.

While Effective Yards has some of that going on, it can also mean something akin to success yards--is a 6 yard run on 2nd and 15 really good? Is it effective? Are those effective yards? Is getting 4 yards on 3rd and 5 effective? "Oh he racked up a lot of garbage time yardage, but he wasn't really effective all day."
Because effective if sort of a catch-all, subjective descriptor, I think it's meaning will be inferred as differrent things by different readers/listeners.

Whereas that bigger mouthful, Equivalent, implies to me that we're sort of stacking up every play and every game to see which one stands taller than the next.... tallest one wins.

by cd6! (not verified) :: Sat, 07/12/2008 - 2:13am

Here's another vote for "equivalent yards."

"Effective yards" isn't bad either for that matter.

by Lou (not verified) :: Sat, 07/12/2008 - 2:36am

Baseball Prospectus expresses things in terms of runs because that’s how baseball people think. Players are listed with runs scored and runs batted in. How many points does a star football player generally create in a good season? Who knows? How many runs does a star baseball player generally create in a good season? Everybody knows the answer: 100.

idunno, ask anyone how many touchdowns a good qb, rb, or wr scores in a season, I think football fans have a feel for that. and of course EqA and EqERA are rate stats fit to normal BA and ERA's scales, whereas VORP or EqR aren't scaled. at least as i understand them. so with DYAR you're taking a counting stat and attempting to scale it(sort of) to conventional stats that just seems wrong.

Once again, this comes down to accessibility to the general public. There’s no reason to have two statistics that measure the exact same thing in almost the exact same way. That’s confusing.

if the problem is the general public, then don't post DPAR in quick reads and just post it on the individual stat pages on this site. i felt your comparison to celsius and fahrenheit was apt, i don't get confused when i see both of them on a thermometer (or inches and centimeters on a ruler), i use the one that makes more sense to me. so why not include both to make more sense to the maximum number of people.

i still say DYAR is a step backwards. before, i could tell my friends to look at these cool stats that say how many points a player was worth to his team. i think being able to say "points" was key, because no one else does that. it set football outsiders apart and said that you guys look at things differently. people intuitively know that the player who scores the touchdown doesn't own responsibility for the score, and DPAR was a step toward splitting up that responsibility, which is exciting.

now i would just say look at these stats that say how many yards this guy contributed to his team, it doesnt have the same impact. points are just more compelling than yards.

don't get me wrong i see the benefit of true yards for quick reads, just don't kill DPAR.

as to the naming thing. I didn't really have a problem with "true yards," but i like the suggestion of "equivalent yards" it conveys what the stat is pretty well, at least to those who are familiar with BP's baseball stats.

by Jerry (not verified) :: Sat, 07/12/2008 - 2:46am

More thanks, Aaron. I like "effective yards", then "equivalent", and "true" last.

Re #2:

DVOA involves adding the result for every play, so it will reflect a team's choice to run or pass. Trying to develop something that would try to adjust that for weather is speculative at best; better to just reflect what actually happened than try to outguess coaches.

by Staubach12 (not verified) :: Sat, 07/12/2008 - 8:41am

I like both "Effective Yards" and "Equivalent Yards." I hate "True Yards." The latter term makes you sound far too confident in the accuracy of your stats. You are not determining truth.

by nat (not verified) :: Sat, 07/12/2008 - 9:08am

The scale is still wrong, though. While an average 200 yard passing game might be about 200 "true" yards, an average 350 yard game is not going to be 350 true yards. If fact, 350 true yards would mean you played a grade-C game, but threw the ball a lot - not a "true" 350 yard game as a fan would see it, but instead an inflated one.

Also, it seems that every position is rated on a different scale. QBs are rated in "Kitna-yards". Wide receivers are rated in "Burress-yards". RBs are rated in "Fargas-yards". But there's no universal yard measure to allow us to compare players at different positions.

So, while re-centering things on average efficiency is an improvement, you still have yards that don't line up with real yards, and that don't even have a consistent value.

This is asking "true yards" to do too much. They can't be compared usefully to the typical value of a 350 yard game and at the same time highlight the value of first downs, TDs, and turnovers.

by Scott de B. (not verified) :: Sat, 07/12/2008 - 9:35am

How about "Adjusted Yards"? Short and to the point.

by Darth Goofy (not verified) :: Sat, 07/12/2008 - 9:59am

re #12:

DPAR does not indicate how many points a player scores, as indicated by Aaron above. The points referred to are like a rating style of points. Therefore, it doesn't really matter if you say points or yards, except that the yards are more easily identifiable to the game of football, whereas the points are just a statistic.

For example, Player A and B had 12.6 and 15.5 DPAR in a game. What does that tell us? Not that they scored 12.6 or 15.5 points in the game. We need to know more about the scoring system, like what the average or high value was for that game or day. Even knowing that 0 DPAR is replacement level doesn't tell the whole story, because it doesn't attempt to describe how well that player played for the day. However, those same players (both are running backs) had 100 real yards for the day. Their EqYards were 150 for Player A and 30 for Player B. This certainly tells us something about how that player performed for the game without knowing anything else aboout the game. Player A did really well, although the real yards don't really show that while Player B had a terrible game but had lot of garbage time yards or something like that.

Anyway, I probably misunderstand what DPAR really is as well... but that is how I have always viewed it, and I look forward to EqYards and D'YAR (best pirate impression).

by marcusjm (not verified) :: Sat, 07/12/2008 - 10:21am

Here's another vote for "Effective Yards," or at least "Equivalent Yards" over "True Yards." Although I kind of wonder: why not go with something like "Player Rating" or "True Rating." Football fans are already used to the word "rating" describing a fairly arbitrary scale and using it understand how well a player did, although only for QBs. I understand "yards" is a bid for accessibility, but then you end up needing to explain why your stat gives Adrian Peterson's record-setting game a lower yard total ("True Yards," but still "yards") while still protesting that "Peterson’s totals of 253 True Yards and 91 DYAR still end up as the best of the year by a significant margin," which just makes this reader confused about why his actual yards had to be converted into a different kind of yards in order to be more properly understood. But... at least "Effective Yards" would be better than "True Yards."

by MC2 (not verified) :: Sat, 07/12/2008 - 10:49am

I like either "Effective Yards" or "Adjusted Yards". They both tell you that you're talking about a different kind of yards, without giving the stat an overly "nerdy" feel.

"Equivalent Yards" requires too much explanation, while "True Yards" sounds somewhat arrogant.

If I wanted hubris, I'd subscribe to BP.

by GBS (not verified) :: Sat, 07/12/2008 - 11:29am

Don't be afraid to let them show.

Your true yards are beautiful - like a rainbow.

by Mike (not verified) :: Sat, 07/12/2008 - 11:58am

So what does it mean, exactly, when a player (Billy Volek) has negative true yards?

by Gerry (not verified) :: Sat, 07/12/2008 - 12:11pm

OK, since you asked for feedback, or at least suggested you are open to feedback, let me vote against calling it True Yards. One reason jumps right out to me, and let me cherry pick some other words from your post, Aaron:

"To but it bluntly, there is a portion of the readership which seems to believe that our stats are more accurate than they really are, and they often try to use those stats to do things they weren’t really meant to do."

It seems to me calling something "True" makes it sound as if you are so confident that this is the definitive measure that it would encourage this very thing.

Further, I think that you and BP have a good symbiotic relationship going. Adapting their nomenclature will only help to serve both of you. People who are open to or who have learned a bit about EqA might find it more accessible to then find out about EqY (even though they are very different in calculation, they are both attempting to translate in form overall performance back to the metric that is more commonly accepted).

I lean towards EqY, but I think that True Yards isn't right; they aren't True Yards. They are an adjusted calculation that gives a truer picture, but not THE true picture.

My 2 cents.

by Bob in Jax (not verified) :: Sat, 07/12/2008 - 12:15pm

Thank you, Aaron. When I first read about the new stats, I was very unsettled, because as I perused the tables of examples it did not look or feel right to me. Being pressed for time (I was at work), I did not investigate further or comment, but planned to come back later and do so.

Then, the invaluable Mr. Gower pointed out some problems, and you responded. Reading the new stat example tables, I feel comfortable. I think this will work well. It is easy to understand for the slightly statistically/logically challenged, and reads quickly. Obviously, time will tell, but I think this one will go over well.

One of the (many) things I love about this site is that the founder is open about issues and eager to correct them. You have a reader for life.

Oh, and I vote for "Effective Yards", but either of the other two names would not offend me. I like the stat.

by The Hypno-Toad (not verified) :: Sat, 07/12/2008 - 12:22pm

14 - "If it's truth you're interested in, Dr. Tyree's philosophy class is right down the hall."
―Indiana Jones

by Alex (not verified) :: Sat, 07/12/2008 - 12:30pm

My vote goes to "equivalent" yards, or "effective" yards. They're both better than "true" yards.

Thanks for responding to my question, but I just don't see why you can't still make DPAR available. Is it just a matter of cluttering up the pages? Or would it take too much time to compute both DPAR and DYAR (since apparently the process is slightly different)? Could we have DPAR on the Premium DVOA database, or something like it? Is the DYAR/DPAR ratio basically just (100 yards)/(7 points), as Pat suggested earlier?

by NF (not verified) :: Sat, 07/12/2008 - 12:32pm

If DYAR is not comparable between positions, was DPAR at all comparable between positions? Was a RB who had a DPAR of 20 equally valuable to the team as a WR who had a DPAR of 20? Is the answer technically yes, but the confounding effect of QB performance and passing game effectiveness render it a meaningless comparison?

by NewsToTom (not verified) :: Sat, 07/12/2008 - 12:51pm

Thanks, Aaron, True Yards actually makes some sense now. I think you'll still face resistance, because it still looks weird to see good players like Purple Jesus have more actual yards than "True Yards", except if it makes sense that they do.

Re #20
He was really, really atrocious when he played? C'mon, what do you expect from 3/10, 6 yards, with an INT and 2 sacks for 7. 12 plays, -1 net yards, and a turnover. Oh, yeah, and he also fumbled the ball away at his own 7, though I'm not sure if that was a pass or run play.

by MJK (not verified) :: Sat, 07/12/2008 - 1:32pm

DVOA involves adding the result for every play, so it will reflect a team’s choice to run or pass.

Right, but hence it also inherently reflects a team's past tendency towards running or passing.

Consider the Pats last year. They had a decent running DVOA, an amazing pass DVOA, and because they passed a lot more than they ran, they had an amazing total DVOA. Put simply, if a team succeeds 60% of the time running, and 93% of the time when passing, and then runs 10 running plays (succeeding on six of them) and 90 passing plays (succeeding on 84 of them), then they will have succeeded on 90% of their plays. So, using DVOA to predict how they would perform against an "average" defense would predict them to succeed 90% of the time.

Yes, DVOA is more sophisticated, in that it compares these success percentages to league averages, allows for "partial" and "extra" success by using success points, and adjusts for opponent defense, but at it's heart it's measuring how likely an offense is to succeed. If this is not, at its heart, how DVOA works and I'm fundamentally misunderstanding the system, please correct me.

I'm trying to figure out how Aaron was trying his weather adjustments. The only way that's obvious to me, in my above, very simplified example, is to estimate from games with weather how much weather reduces an opponent's success chances. Say it tends to half the chance of a pass play being successful, and doesn't affect running plays. Then, in the above example, the team's chance at succeeding at a pass play would be roughly 46%, and at a running play still 60%.

So how often does the "weather adjusted" metric predict success? I don't think the prediction algorithm Aaron uses actually games out playcalling decisions (e.g. he doesn't simulate a game using some sort of decision theory AI for play selection, and then use specific DVOA's for the teams at estimating success of each play). He just extrapolates a total DVOA from past data. So how does he do that? I don't see how he could take changes of playcalling into account...or if he does, I'm curious to know how? The most primitive way would be to extrapolate past playcalling tendencies--so assume the team calls 90% pass, 10% run, which would predict, in winds, a success rate of 48%. But of course, the coach would be smart enough not to stick with 90% passing if it only works 42% of the time and running works 60% of the time, so maybe he would run more and pass less, leading to a greater success rate than a primitive weather adjustment would allow...

by Joseph (not verified) :: Sat, 07/12/2008 - 2:23pm

Hate to pile on, Aaron, but I vote for effective yds, then equiv. yds., over true yards. As mentioned, it makes it sound like these are TRUE values, vs. the approximate worth that you are trying to make them.
Is there a way with DVOA, DYAR, or DPAR (r.i.p.) to compare players ACROSS positions? I always assumed that DPAR did that--QB's get more overall value because they tend to have more attempts (and completions) than most RB's, and RB's have more carries than WR's have catches, then voila!--QB's (or at least the better ones) have more DPAR than RB's, who have more than WR's. Will (________) yards be as comparable, or was DPAR not designed to do this?

On another note, I'm jealous at those who already got their PFP. 1--I've been painting most of my house here in Mexico. 2--I have to wait till my pastor flies in from New Orleans on Friday to get my PFP--and THEN I'LL HAVE TO WAIT TILL HE LEAVES TO READ IT!!! (mostly because this is the first time he's come--and also because I don't want my wife to kid me for being a bad host :b

by James, London (not verified) :: Sat, 07/12/2008 - 2:30pm

My Prospectus arrived an hour ago. Woo-Hoo!

by CarolinaNick (not verified) :: Sat, 07/12/2008 - 3:10pm

Why not just put dpar on the premium database? Casual fans won't have it there to confuse them, and more serious fans could look at trendlines over several seasons without having to do their own calculations.
Of course, if you are planning to convert all of the old data to dyar it's a bit of a moot point.

by Felden (not verified) :: Sat, 07/12/2008 - 3:29pm

Re: 21.

It means he shouldn't have left his bed that morning.

by Gerry (not verified) :: Sat, 07/12/2008 - 3:35pm

"My Prospectus arrived an hour ago. Woo-Hoo!"

I am freaking jealous. According to Amazon/USPS, mine has been sitting in Memphis for about 4 days now.

by ArchNerdUW (not verified) :: Sat, 07/12/2008 - 4:20pm

For what it's worth, it seems like "Effective Yards" would be the best terminology going forward. To echo some of the other comments and the posting in general, "equivalent" begs the question "Equivalent to what?" "True" does seem to be setting up a ton of pitfalls and snarky posts, if last years reactions on the FoxSports website was any gauge.

Also I just got my copy of the book. 1st time reading it and I really don't know how (or why) I ever tried watching football without it. Keep up the good work.

by young curmudgeon (not verified) :: Sat, 07/12/2008 - 5:11pm

MJK, No. 2: “Equivalent” begs the question “Equivalent to what”--good point, but it doesn't "beg the question," it "raises the question." To "beg the question" means to frame the inquiry in such a way as to assume the truth of the very point being questioned. (Wow, that's an awkward way of putting it.) You may now leave fourth period English and return to a stimulating discussion of football and statistics.

by BD (not verified) :: Sat, 07/12/2008 - 6:59pm

I have some reservations. As many have put it, True Yards does not seem to accurately describe what the statistic measures.

But closer to the point, I do not understand exactly the change to a yardage scale. My understanding of the need for FO stats was to rectify the "Kitna" situation of a player racking up ridiculous conventional stats but not helping the team win/score or likewise, a QB who throws for 200 yards but doesn't get them with 10 yard gains on 3rd and 15's.

In other words, the need seemed to be to translate conventional yardage stat into one that showed, over the course of a game, who was most instrumental to winning a game.

Putting this information on a yardage scale seems misleading to me, because as most FO readers and some football fans understand, yardage is not what people want to know (except for your fantasy team). I want to know on Monday, "OK, Trent Edwards threw for 131 yards, but how beneficial were those yards to the team?" Putting the answer back on the yardage scale makes little sense to me, because if I wanted to know how many yards he threw for, I can just look in the paper and see 131 (and subsequently become depressed).

The scale you are describing is not truly "yards" anyways, as it incorporates situation, down & distance, incomplete passes, interceptions, etc. As you have noted, it's really "accumulated success points."

I understand this is what baseball prospectus does, and we're not really here to debate BP. But as other posters have noted, I also take issue with taking a statistic and mapping it onto an imperfect stat (i.e., EqV and batting average). Readers interested in finding better statistics are likely to be sophisticated enough to understand the limitations of the original scale and be interested in finding alternatives.

I would suggest, and I know this may sound somewhat radical, just giving readers the accumulated success points adjusted for situation and place. Fans are used to adding up points, as they do for fantasy teams. With a little experience, people would come to understand the scale with a small amount of help (i.e., A play that nets a first down or makes a 1st down more likely gets 1. Extra yards or scores net more points. Turnovers assess a penalty.)

by Waverly (not verified) :: Sat, 07/12/2008 - 7:33pm

As soon as I saw the term "True Yards" I knew it would cause trouble. Would that imply that the yardage listed in the NFL game stats were actually "false yards" or "sham yards"?

I thought "Effective Yards" would be best.

If you think three syllables is too long for the adjective, then maybe "Honest Yards". But maybe that's too judgmental.

A one syllable alternative is "Good Yards".

So I'll vote for "Effective Yards".

by Peder (not verified) :: Sat, 07/12/2008 - 9:18pm

I'd vote for equivalent yards, shortened to EqY and pronounced 'ecky'. "Sure he threw for 320 but his /ecky/ was more like 120."

by The McNabb Bowl Game Anomaly (aka SJM) (not verified) :: Sat, 07/12/2008 - 10:01pm

I like "Adjusted yards," but I seem to be in the minority on that. It just makes more sense to me than "effective yards." I hate the name "true yards" because that's exactly what they aren't.

I hope we can still see DPAR listed on this website in the stats tables, for the sake of the hardcore fans, but I understand why you don't want to put it in Quick Reads.

by Reinhard (not verified) :: Sat, 07/12/2008 - 11:39pm

Another thought on weather prediction:
If you play worse in bad weather that reflects a fundamental weakness in your team. If you still play well, or better, it shows that you are adaptable and multi-facted, and your dvoa (sorry! your dyar...) will reflect a fundmamental strength in your team's offense.
If weather does affect certain techniques and matchups, then those are tings that dyar can't take into account anyways

by DB (not verified) :: Sun, 07/13/2008 - 12:10pm

One more vote here for "equivalent", "effective", or "adjusted" yards - in that order. To me in my head I keep thinking that, true yards = actual yards, which is exactly wrong.

by Temo (not verified) :: Sun, 07/13/2008 - 1:30pm

I'm actually quite surprised that a large amount of people have a hard time accepting "True Yards".

by Moridin (not verified) :: Sun, 07/13/2008 - 1:43pm

For me, True/Real doesn't work, since that clashes with the implication of his normal yards (aside from the other connotations).

Equivalent yards is awkward since the scale is the same and Equivalent to be means 'equates', aka these 300 yards are really equivalent to these 250 yards. Equivalent would work better for me as a name if it was a different scale.

Effective/Useful/Important doesn't really work, because by implication, the value shouldn't be larger than his normal yards. Having a 300 yard game, and saying only 270 of it was effective works, but having a 300 yard game and saying 360 of it was effective doesn't come across easily.

Adjusted by itself leaves out the how and/or why of the adjustment, but brings the least negative implications. I'd vote more for Adjusted Effective Yards (AEY) more than anything if we are stuck in the yard scale, which leads me to...

Since this is basically a value that is to be used in direct comparison of an existing stat (and it really should be right next to total yards in the table given this), how about changing it to a percentage? To me, saying he was 120% as effective/useful as his stats imply is what it is trying to say anyway. If Effectiveness is a little to broad given the other conventional stats as well, then Yard(age) Effectiveness works for me as well.

So my vote is switch to percentage & Effectiveness, switch and Yard Effectiveness, and Adjusted Effective Yards (AEY) if you feel you have/want to stay in yards.

by Pat (not verified) :: Sun, 07/13/2008 - 2:57pm

When Jon Kitna throws the ball 50 times and ends up only completing half his passes, with 350 yards and three interceptions, he won’t have 300 True Yards. That’s not a 300-yard game that really has the value we tend to associate with 300-yard games.

Is True Yards calculated based on average performance or summed over all plays?

If it's summed over all plays, doesn't it have a bit of an issue in that it will be pace-dependent? If a game has ~80 or so plays, a QB who performs "good" will put up more than 300 yards, and so you would say that he had more than 300 "True Yards."

Average performance would seem to make sense, but in that case you'd get situations where you'd be saying "Manning had 400 yards passing, which is really 350 True Yards." Which means it ends up looking like he did slightly "worse", but really what you're saying is that in a typical football game, that would be 350 yards passing.

If that's true, then I'd really vote for "Equivalent Yards." True Yards seems like it should be compared to Actual Yards. "Equivalent Yards" is fairly obvious that it's comparing things to a common baseline.

Either that, or you would need to point out in each Quick Reads "Remember, True Yards should be around 300 for a good day for a quarterback, 100 for a running back, and 100 for a wide receiver. A quarterback having a good day in a fast-paced game might end up with more than 300 yards, but his True Yards will still be around 300."

by Pat (not verified) :: Sun, 07/13/2008 - 2:58pm

As soon as I saw the term “True Yards” I knew it would cause trouble. Would that imply that the yardage listed in the NFL game stats were actually “false yards” or “sham yards”?

Uh, yes? Most fans already have a concept of "false yards" in the real stats. Hence "garbage time".

by Sergio (not verified) :: Sun, 07/13/2008 - 3:53pm

re: 7
"Although seeing as how your job is, after all, at least related to exhaustive statistical modeling, it’s somewhat alarming that you still use excel spreadsheets for your main calculations. :)"

I can't stress this point enough, in a serious way. Aaron has mentioned before (the Bill Simmons hour-long podcast comes to mind) that he's been suggested different methods but doesn't feel comfortable with anything but Excel (I'm paraphrasing, but that's the gist IIRC).

My question is... WHY? Even a simple mysql database would yield better results, methinks (particularly if you clusterize, which wouldn't be expensive), and these days *anything* can have a simple php/.NET graphical front with mind-numbingly easy interface (hell, even webforms would suffice). And if you're worried about expenses, I'm sure you can find several talented individuals here that are willing to help out in such a venture...

All I'm saying is, please consider it. More data volume can only help the stats.

by BD (not verified) :: Sun, 07/13/2008 - 4:04pm

Re: 43:

Since this is basically a value that is to be used in direct comparison of an existing stat (and it really should be right next to total yards in the table given this)

This is exactly the issue I was referring to in my post. "True yards" is not really measuring yards, so this comparison is not exactly appropriate. "True yards" is a different measurement scale of which yardage is a part of, but it also includes other things. It has then been transposed to another scale to make it look like yardage.

So statistically, comparing "True yards" to yards directly is inappropriate, an apples to oranges comparison.

by Phill (not verified) :: Sun, 07/13/2008 - 5:16pm

It's worth mentioning that excel has several, well documented flaws in its stats packages that make it in several cases plain wrong, and undeniably so.

by Kevo (not verified) :: Sun, 07/13/2008 - 7:27pm

"True Yards" gives me a John Wayne feeling. It's awesome.

"Equivalent Yards" makes you sound like one of those pocket protector-wearing sabremetricians who sits at his computer all day in his underwear and lives in his mother's basement. "Equivalent" is probably more accurate than "True," but you've got to have some balls when you introduce new stats to morons who are too lazy to accept change. You've got to force the stats onto them.

by throughthelookingglass (not verified) :: Sun, 07/13/2008 - 10:19pm

Wasn't going to comment, but this annoyed me.

Baseball Prospectus expresses things in terms of runs because that’s how baseball people think. Players are listed with runs scored and runs batted in. How many points does a star football player generally create in a good season? Who knows? How many runs does a star baseball player generally create in a good season? Everybody knows the answer: 100.

How many points does a star running back create in a season? 90. 15 touchdowns, which are more important to the football statistical lexicon than RBI is to baseball. Everybody knows that star baseball players create 100 runs a season? Even the old-school baseball fans I know don't think that a 100 RBI player contributed 100 runs to the team. I just don't think there's that much of a difference between TDs and RBI to justify this decision.

Another reader wrote "[DYAR] is tantamount to baseball sabermatricians moving from a runs-based system to adjusted batting average just because old-school fans love BA." Apparently, he didn’t know that Baseball Prospectus does precisely this. That’s what Equivalent Average (EqA) is meant to be, "adjusted batting average." It measures all offense, not just hits per at bats, but it does it on a scale the average person understands, where .300 is good and .200 is bad.

I know you're affiliated, but I don't think that "BP does it is much of a defense. However, what you're doing is similar to BP only using EQA.

Also, can you keep trying to convert to wins? I really don't care if the conversion table is based on the metric system or a base-pi system, I like to think in terms of wins.

by AdamJT13 (not verified) :: Mon, 07/14/2008 - 4:12am

Effective Yards implies that the player was effective for that number of yards, which might or might not be the case. (And is confusing when the number is higher than the actual yardage total.)

True Yards implies that the total is more true than the actual yardage total. It's not, it's just a measure of the true value of the actual yardage total.

Adjusted Yards implies that the actual yardage total has been adjusted to reflect whatever is intended to be reflected. And that certainly seems to be the case, which is why it makes more sense than the other choices.

by Temo (not verified) :: Mon, 07/14/2008 - 8:07am

50. 15? Really? I can remember many great RB seasons that resulted in less than 15 TDs. On the other hand, the number of great baseball players who batted lower than 2nd and had less than 100 RBI, I can count on one hand.

by pawnking (not verified) :: Mon, 07/14/2008 - 8:51am

No comment on the statistics involved, but I do have a suggestion to the process of rolling out changes to your statistics. You can model what the FASB does whenever they consider a change to the Generally Accepted Accounting Princiles (GAAP). They go through the following process:

1) Appoint a task force
2) Prepare a discussion memo
3) Hold a public hearing on the issue
4) Analyze the responses
5) Issue a draft proposing the new standard
6) Hold a new hearing on the draft
7) Analyze responses
8) Issue a final statement.

The advantage to modifying this approach the fit DVOA is it would give you a system of introducing all of your proposed changes in a forum where they can be picked apart before the big announcements, such as the one last week. Changes, improvements, and problems can all be raised by the FO fans you rely upon. When you finally introduce the new stat, everyone will be at least a little familiar with it, and the pushback will be less.

Just my 2 cents.

by Herm? (not verified) :: Mon, 07/14/2008 - 10:19am

FO's attempts at clarifying and improving their methods is the most important message here. To me the best statement was "see if a player’s performance was better or worse than his actual yardage total in that game or that season."

Beyond that, FO's response in the introduction is another great example of caring about their readers, and listening and responding to us.

While the intent is to have the "average person" understand these metrics, I give the current users collectively enough credit that we will adjust to whatever the new nomenclature is and move on. DVOA, DPAR/DYAR, pythagorean wins, Kubiak, etc...every one of these requires some up front effort to understand. True Yards is only our latest homework assignment. I really hope we get a new one each year as the improvements keep coming.

As a future statement, my thoughts are that if the attempts are to appeal to the masses, at some point you may have to draw a line and realize you'll just never reach the people and media who sensationalize football with Kid Rock commercials with phony hits and watch atrocious Al Pacino movies that have eyes falling out.

DYAR rulezzzzz!

by GlennW (not verified) :: Mon, 07/14/2008 - 10:37am

> 'At least this guy mentioned EqA. Another reader wrote "[DYAR] is tantamount to baseball sabermatricians moving from a runs-based system to adjusted batting average just because old-school fans love BA." Apparently, he didn’t know that Baseball Prospectus does precisely this.'

Actually I did know this. Still, I consider EqA to be a secondary derivative statistic, and not as useful as VORP overall. (And yes, I know that EqA is a rate stat regardless; I was just making a general point-- a better example would have been switching from a runs-based scale to a hits-based one.) Appreciate the condescension though. I stand by my point on an objective of maintaining a level of standardization year to year.

by GlennW (not verified) :: Mon, 07/14/2008 - 11:15am

> "On the other hand, the number of great baseball players who batted lower than 2nd and had less than 100 RBI, I can count on one hand."

RBI (as well as runs) are so situationally dependent that this happens quite often in a great offensive season (in particular valuable walk machines are undervalued by RBI-- e.g. Wade Boggs never drove in 100 runs in a season). In any case, I think almost everyone who uses such statistics realizes that runs-based metrics (VORP, RC, EqR etc.) have no direct correlation with RBI or R, but rather an average equivalent offensive contribution to one run scored. That's how I looked at DPAR (without even considering individual TDs) and didn't find that terribly confusing.

by Spike (not verified) :: Mon, 07/14/2008 - 12:08pm

Two thoughts, one about the name and another about the weather. (TOO HUMID HERE THX.)

The idea...was to create a simple number that an average fan could compare to standard yardage in order to see if a player was more or less valuable than his stats otherwise would indicate

Shouldn't a term reflect the ton of time you put into football research and try to move "average fans" up rather than shoot for accessibility? I vote "Real Yards," to communicate it's a improved measure.

Once you corrected for wind speed, the effect of precipitation seemed to be just statistical noise, with no pattern at all.

Would weather play less of a role in DVOA because the teams game plan and execute with the weather already in mind? If the field is windy or muddy, players will choose different options, throw specific passes, cut back less, etc. You have so many options in a typical play anyway, would removing a few change much?

by Temo (not verified) :: Mon, 07/14/2008 - 12:34pm

56. I wasn't trying to say that RBI is a good stat, just that people use it to get a measure of a player. As opposed to TDs... if you told people that a guy got 7 tds but ran for 1500 yards, they'd say he had a good year.

Besides, the red sox used Boggs to lead off a lot in his prime, so he wouldn't be counted under my statement.

by Dave (not verified) :: Mon, 07/14/2008 - 1:48pm

I am just releatively new to following this site. I know the QB rankings take into account strength of opponents played. But do they take into account the offensive line? For example, if Derek Anderson and Ben Roethlisberger switched pass blocking offensive lines? Is this sort of thing factored in? It is just hard for me to see how many QB's could have played any better behind the O-line that Roethlisberger dealt with.

by Alex (not verified) :: Mon, 07/14/2008 - 2:52pm

But do they take into account the offensive line? For example, if Derek Anderson and Ben Roethlisberger switched pass blocking offensive lines? Is this sort of thing factored in?

No, it is not factored in. You just have to remember that, if they both had average pass blocking lines, Anderson's numbers would be worse, and Roethlisberger's would be better. How much better or worse is a tough question, and so far, not enough research and analysis has been done to give concrete answers.

by throughthelookingglass (not verified) :: Mon, 07/14/2008 - 3:02pm

My point was that football people think in terms of numerous stats, including points (touchdowns), and baseball people do the same thing! Other than that, what GlennW said.

by chip (not verified) :: Mon, 07/14/2008 - 3:04pm

#50 I second your thoughts. Both comments struck me as borderline absurd as far as rationale goes. Why not drop DPAR into the Premium DVOA database? Those that have paid their $50 and rely on DPAR to make fantasy and / or betting decisions can still have their cake and eat it too.

by AS (not verified) :: Mon, 07/14/2008 - 3:08pm

#54 Do you write for FO? You seem to miss the consensus on the discussion boards. "Caring, listening, and responding" to their readers? This has been a one way dialogue.

by JCRODRIGUEZ (not verified) :: Mon, 07/14/2008 - 3:12pm

My vote goes to True Yards...and to more Cindy Lauper references, indeed...

by Herm? (not verified) :: Mon, 07/14/2008 - 4:02pm

No, my typing is not that orangey/brown color, funnyman. I don't know what other groups you participate in on this planet, and on what size and locale, but I'd say a mailbag of responses during the DYAR transition is a more than fair response. We'll see how it pans out, but I haven't heard one F-You out of any of the staffers here. Maybe I've been living in the oversized corporate-pharma world for too long, but the fact that they responded is acceptable to me.

Also, you may want to understand discussion boards. They're mostly a tool for us to pretend we're smarter than we actually are. Many of us think complaints or putdowns make us look intelligent. Dissent is an important tool here if used correctly, but it's overused; very few complaints actually merit response.

So why am I bothering now?

Most people only post or write in with complaints, in exponentially greater numbers than compliments. I'd be willing to BET, generally speaking, for each complaint, there are twice as many who are in favor of change but don't post, and twice as many as that who really just don't care and lurk on.

I make sure to toss in compliments when they are due, because the staff here is trying to progress. They do seem to respond to discussion boards, and I really don't want to see them change it drastically based on a bunch of complaining 3/4 wits.

Either way, as I mentioned, IDGAS what they call these yards, because 2 or 3 weeks after the decision is made, most of us will have adjusted to it and it will be a part of the collective user knowledge here.

by Herm? (not verified) :: Mon, 07/14/2008 - 4:09pm

anways, for all the Cyndi Lauper and pirate references, I vote for Goonies.

by GlennW (not verified) :: Mon, 07/14/2008 - 4:28pm

> "and I really don’t want to see them change it drastically based on a bunch of complaining 3/4 wits"

Wow. Actually I've read very little here in the way of braindead criticism, and at the very least it's been honest feedback (none of the "FO is biased towards the Patriots" variety of nonsense). And listening to your customer base is just part of the business when you're charging for a service (as perhaps opposed to the free advertising-based website side of the operation). I don't know what percentage of FO readers are also paying customers, but I have been...

by Herm? (not verified) :: Mon, 07/14/2008 - 5:17pm

GlennW, before you "wow", it was a general messageboard statement, you should be wondering if you fall into the category of "merits a response".
I'm a believer in listening to your customer base, but again, consider the scale of active complainers vs. active satisfied customer. If you draw it up, it looks like:
dissatisfied--> complain
satisfied--> (blank)
how do you reach and measure a silent consensus? If you don't, and you make changes based solely on complaints, the formerly satisfied people now become the complainers - vicious circle, yes?

As long as progress and effective measurement are the goal here, individually I am satisfied.

Anyways, the consensus overall here is to discuss what a statistic should be named, which to me is a minor detail and a slap in the face when you think of the work it takes to roll out the results of an extensive project.

Your individual discussion of year-to-year standardization, it warrants better detail, but from the sound of it, I'd probably disagree. Are you arguing against change or progress here? I guess the question is what do you stand to lose here? Maybe I am completely misunderstanding it, but my thought is that adjusted football statistics and measurements are still in their infancy, and a point based system can not come close to comparing to baseball yet - scoring and football points are not based on a 1:1 scale, and the point margin of error in football (including weather, fumbles, tipped interceptions, and some special teams) is so fantasticly random that the measurement systems here are not quite ready to make consistently great predictions. But because I don't stand to lose anything here, I'm enjoying the ride.

by MC2 (not verified) :: Mon, 07/14/2008 - 11:42pm

#52: "I can remember many great RB seasons that resulted in less than 15 TDs. On the other hand, the number of great baseball players who batted lower than 2nd and had less than 100 RBI, I can count on one hand."

Yeah, but you'd need more hands than a Hindu deity to count the number of guys who've racked up 100 ribbies *without* having a great year. How many guys have scored 15 rushung TDs in a "nongreat" year?

The fact is that both RBIs and TDs are inherently flawed stats that tell you at least as much about the quality of the player's teammates than about the quality of the player himself.

by MC2 (not verified) :: Mon, 07/14/2008 - 11:45pm

Uh, just consider "rushung" to be a tribute to Raiderjoe.

by Richard (not verified) :: Tue, 07/15/2008 - 4:15am

I'd like to vote in favor of Adjusted Yards. Equivalent, True and Effective all sound like terms I won't want to quote to anyone.

by nat (not verified) :: Tue, 07/15/2008 - 9:23am

If Aaron had announced "True Fumbles" which converted everything back to the equivalent value of turnovers, or "True First Downs", we would have all laughed at the joke. But "True Yards" has the same problem.

FO has taught us that yardage is a poor measure of success. And now they give us "True Yards". Bleh.

by Eddo (not verified) :: Tue, 07/15/2008 - 10:20am

72: FO has taught us that yardage is a poor measure of success. And now they give us "True Yards". Bleh.
I've stayed quiet on this, mainly because like Pat and Herm?, I feel that the scale the stat is in is not as important as what it's measuring (success in helping your team win).
However, to address the above quote, this is not what FO is doing. Didn't the also teach us that points scored is a poor measure of success? Why was DPAR "bleh" then?
Maybe Aaron's been unclear in his description (I believe I understand him, though), but "True Yards" and "DYAR" are not actually measuring yards. They're measuring a new scale of "success points," that's all. The use of yards is to be able to say, "So-and-so threw for 285 yards today, but because of his third-down percentage and turnovers, it was really about as effective as a normal 250-yard day."

by Eddo (not verified) :: Tue, 07/15/2008 - 10:23am

73 (me): Should say "Why wasn't DPAR 'bleh' then?"

by Mike (not verified) :: Tue, 07/15/2008 - 11:14am

I'm still not exactly certain how True Yards and DYAR measure something different. True Yards minus DYAR equals how a replacement level RB would have fared if he had all of your carries, right?

by NewsToTom (not verified) :: Tue, 07/15/2008 - 12:11pm

Re #75
My best explanation of "True" Yards:
It's how many yards a player should have gotten on the chances he got based on his overall performance.

I think it's probably best to think of both "True" Yards and DYAR as coming from DVOA, but not necessarily having anything to do with each other.

by GlennW (not verified) :: Tue, 07/15/2008 - 12:21pm

> "Didn’t the also teach us that points scored is a poor measure of success?"

Really? Points scored/allowed is a "poor" measure of success? Sure, in the short term points can be somewhat deceiving as opposed to team DVOA (just as RS/RA in baseball also can be deceiving relative to the underlying stats), but points are inarguably the basis of the game, not yards. I know this has been beaten to death, but it's only my preference (not an absolute requirement for my consumption) that the context-adjusted player total value statistic be presented in units which form the actual basis of the game. Or at least provided as an alternative, consistent with FO's own historical precedent and for ready comparisons between past and present.

by nat (not verified) :: Tue, 07/15/2008 - 12:26pm

DPAR wasn't "bleh": it scaled accumulated success points (with adjustments for replacement-level baseline, situation, repeatability, and opponent) to points. Success points were always intended to correlate well with points scored, not yards gained.

DYAR still correlates well with points (with adjustments as above), but is stated in terms of yards. A new arrival at FO seeing "Defense-adjusted Yards Above Replacement" would naturally think that DYAR was based on yards, or could be seen as "extra yards over a replacement that the player was worth" - which is just not true at all.

Scale, and what you call it, do matter. Remember that DPAR was created because "Defense-adjusted Success Points Above Replacement" didn't help people understand the size of the extra success.

D-Points-AR (DPAR) gave you a scale. Success points correlate well with points, so the scale makes sense. And people know how important a point is. (It's how the winner is determined.)

D-Yards-AR (DYAR) gives you another scale. But success points don't correlate well with yards, so the scale is less reliable. And, as FO has shown, people don't really understand how important a yard is, anyway.

DPAR: well-correlated to a scale that is important.
DYAR: less correlated to a scale that is less important.

I say again: "bleh".

by nat (not verified) :: Tue, 07/15/2008 - 12:55pm

it’s my preference that the context-adjusted player total value statistic be presented in units which form the actual basis of the game

Amen, brother.

Some people say that D-Wins-AR is the holy grail of player value stats. But since few players play on more than one unit, and since the offense is mostly concerned with scoring before the other team does, DPAR is pretty good.

by Waverly (not verified) :: Tue, 07/15/2008 - 3:34pm

"Adjusted Yards" sounds too similar to "Adjusted Line Yards".

I know that they are different kinds of numbers applying to different kinds of players, so they aren't strictly conflicting stat names. And "Adjusted Yards" still sounds a lot better to me than "True Yards". But "Effective Yards" or "Equivalent Yards" is less likely to be confused.

by Herm? (not verified) :: Tue, 07/15/2008 - 4:30pm

RE: Points vs. Yards

Points can be useful in team based statistics, so if the adjusted value over average can be successfully translated into points in team-type game simulations, I'd be happy to read it (and I think FO would own an island.)

But when approaching a football game plan (not gambling or fantasy), successfully executing plays is the primary goal; points are an incidental benefit. It's a very odd sounding approach, considering the result of a football game is based on the idea that the team with more points wins the game. But this is a sport where scoring only occurs a couple of plays per game out of 100.

I have a hard time placing value on an individual based solely on scoring points, particularly in the most recent evolution of the game (runningback by committee), when the successful execution of a drive is ultimately a team-driven accumulation of yards by many players. With all that effort, I find it incorrect to award better value to Mike Vrabel's 1 attempt/1 TD when the rest of his team took the ball 60-80 yards. Again, whomever has the ball when it crosses the goal is incidental.

by scott (not verified) :: Tue, 07/15/2008 - 5:02pm

Adjusted Yards, or AY!

In keeping with the overall pirate theme.

Been watching the kvetching and gnashing over the new stats and I think a lot of the discussion has been backwards. Everyone is arguing over the goodness of the statistics.

But the statistics are good. DYAR and AY are more accurate *in what they're trying to measure* than DPAR.

In fact what people are wrangling over when they argue over the goodness of the statistics is actually whether or not what the statistics measure is good.

It's the difference between talking about how to fight a war the right way and about if it's right the fight the war. Follow?

Actually I'm not sure I follow myself. All I'm saying is Aaron's in a tough spot using statistics to measure massively complex systems. We dummies (and dumb editors at big web sites) always want to take numbers and assign broad meaning to them when that's not really possible.

I appreciate his efforts to balance statistical rigor with accessibility. If he errs on the former side, ESPN has no use for him. If he errs on the latter side, the FO faithful with some statistical knowledge revolt.

I don't envy him the task of this transition.

by GlennW (not verified) :: Tue, 07/15/2008 - 5:27pm

> "Points can be useful in team based statistics, so if the adjusted value over average can be successfully translated into points in team-type game simulations, I’d be happy to read it"

I'm pretty sure that's exactly what DPAR does (or did), to whatever degree of accuracy. Nonetheless DYAR similarly considers team situational context; it's simply employing a different baseline unit-- yards. (Others have correctly pointed out that we could use Fumbles Above Replacement for performance measurement; it'd be completely counterintuitive and clumsy, but sure, you could still rank and rate players by this unit.)

Of course the RB who scores from the 1 on 1st-and-goal doesn't accumulate 7 DPAR (or whatever the total DPAR value is for a long TD drive, as the replacement-level average expected score is greater than zero). But in a long TD drive of say, 10 positive plays and 2 negative ones, yes, I'd prefer to see the individual-play components of that drive represented in fractions of DPAR cumulatively adding up to 7 DPAR (or whatever) as opposed to 60 DYAR, just as an example. In a perfect system (which doesn't exist obviously), over a season such a statistic tells me what a player (or a unit, such as the passing offense behind QB X) contributed to his team *on the scoreboard*, as opposed to the yardage stat sheet. But again, that's only my preference.

by The McNabb Bowl Game Anomaly (aka SJM) (not verified) :: Tue, 07/15/2008 - 5:33pm

Re: 76

I think your explanation of True Yards is misleading and possibly flat out wrong.

True Yards represent the value that would be accumulated if a league-average QB threw for that many yards.

According to NewsToTom, Brady "should have gotten" 7,101 yards based on his opportunities. I think this is wrong. According to my understanding, what that number means is that Brady's performance was a good as an average QB throwing for 7,101 yards. Now, obviously an average QB would throw for fewer first downs and TDs and more INTs, so that's how Brady was able to squeeze 7,101 yards' worth of value into only 4,760 actual yards that he threw. He gets much more value per yard thrown than an average QB (and he threw a lot), and that's why his True Yards are so high.

True Yards don't approximate some theoretical ideal yardage number. They measure value contributed.

by armchair journeyman quarterback (not verified) :: Tue, 07/15/2008 - 9:44pm

what is truth?

count one vote for "equivalent yards" or even "eYards." conveys the point without unnecessary footnotes (or philosophical conundrums)

by SteveNC (not verified) :: Tue, 07/15/2008 - 10:09pm

I vote for adjusted yards as well, as that seems to be what's going on.

by nat (not verified) :: Tue, 07/15/2008 - 11:49pm

81: Herm?

DVOA, DPAR etc are based on success points, which measure progress towards scoring. Not scoring itself. There is noone in their right mind that thinks all plays are worthless except touchdowns.

You got it right. Brady's 7,101 "true yards" are how many yards an average QB would have to throw for to deliver the same value.

Let's call them "Kitna Yards". Or, since we're going for the gusto here, "True Kitna Yards".

by Matt (not verified) :: Wed, 07/16/2008 - 9:08am

For example, the average running back over the past few years has gained 4.16 yards per carry, and Adrian Peterson’s DVOA of 16.4% ends up as 4.85 yards per carry.

Shouldn't that say that his 4.85 YPC ended up as a 16.4 DVOA? Or am I missing something? Yards per carry still happens in the real world, right, and is not something caused by FO or generated in Excel.

by Mike (not verified) :: Wed, 07/16/2008 - 9:33am

Let’s call them “Kitna Yards”. Or, since we’re going for the gusto here, “True Kitna Yards”.

I'm sold. KITNA goes well with KUBIAK, and basically is a measure of how many yards Jon Kitna - the replacement level QB - would have needed to get the same value as a given quarterback. Jon Kitna would have needed to throw for 7,000 yards to be as good as Brady last year. Makes perfect sense to me.

by nat (not verified) :: Wed, 07/16/2008 - 9:56am

To be fair, Kitna is more of an average QB (in terms of per-play effectiveness, that is, DVOA) than a replacement level QB.

I shudder to think how many "Grossman Yards" Brady had last year. (more than 9,000, maybe?)

by nat (not verified) :: Wed, 07/16/2008 - 10:59am

One more piratical nominee for renaming "true yards":


Buttercup: Westley, what about the Y.O.U.S.'s?

Westley: Yards Of Unusual Size? I don't think they exist.

by Matt (not verified) :: Wed, 07/16/2008 - 11:00am

Re 88 -- my own comment -- maybe I am missing something. Maybe Aaron meant that AP's DVOA led to a True Yards score of 4.85 YPC? I am still confused. Too many different kinds of yards to track now.

And whatever piratey goodness DYAR most certainly has, "True Yards" sounds like a product for your lawn.

by Temo (not verified) :: Wed, 07/16/2008 - 11:22am

90. ITS OVER 9000!!!!!!

I'm sorry. Click the name for the reference if you're not a total nerd like me.

by Fire Millen (not verified) :: Wed, 07/16/2008 - 11:39am

I'm not loving True Yards, but effective and adjusted were what came to mind first so they can't be any good. I propose Success Yards which can be very easily shortened (acronym'ed?) into ...... SucYa's.

by nat (not verified) :: Wed, 07/16/2008 - 2:44pm

re 93
Apology accepted. That link brought tears to my eyes. I had not seen that before, and hope never to see it again.

by Temo (not verified) :: Wed, 07/16/2008 - 9:37pm

95. In my defense, most guys my age saw that show in youth (I'm 22). Also, you can't go wrong with 3.7 million youTube views, right? Umm... right?

by Scott C. (not verified) :: Thu, 07/17/2008 - 2:07am

Aaron, thanks for setting me straight on the foundations of the success points. I'm a bit disappointed that they aren't rigorously calculated from first principles -- as I had assumed 4 years or so ago when first finding this site and reading explanations about DVOA and DPAR. However, I suppose there is more information in "The New Hidden Game of Football".

You also mention that this still all runs in a spreadsheet -- It might be a challenge to shift at first, but a true database will empower orders of magnitude more calculations, data, and analytics on your dataset. I imagine that would be a major overhaul and take some expertise and $$ that FO may not yet have, and I'm biased since I deal with predictive analytics on data that grows at ~40 million "plays" a day for a living these days.


I agree that "Effective" is much better than "True" and suffers less 'huh?' factor than "Equivalent".

However, one poster above noted that since this isn't based on yards, its based on Success Points, why not call it


That would be my favorite, and perhaps easier to explain. Rather than "what is true about it?" or "What is effective about the yards?", you get "what defines successful yards?" which is MUCH more on point with how the system works and what it is trying to imply.
This way, you can say things like: "a TD on third and long is worth a LOT of Success Yards" or " his fumble caused him to lose about 20 Success Yards."

I really think that is the easiest sell to the non-geek public.

by GlennW (not verified) :: Thu, 07/17/2008 - 10:08am

Question: is the "True Yards" statistic presented in PFP 2008?

by coldbikemessenger (not verified) :: Thu, 07/17/2008 - 8:06pm

re 98

by anotherpatsfan (not verified) :: Thu, 07/17/2008 - 10:28pm

Re 98, 99.

No, actually it is not in the book. Which is a good thing, since True Yards as it existed as of the time of book publication/release was FUBAR, or at least FU, until Aaron adjusted the calculation.

PFP 2008 has DYAR and YAR, and regular ol' yards, but I have not seen any yards of the True/Effective/Equivalent/Success/Actual/Messed Up/any other adjective/ variety.

by Waverly (not verified) :: Thu, 07/17/2008 - 10:37pm

re 99:
"True Yards" is in PFP 2008? I didn't see it -- where did you find it?

I had the impression that "True Yards" was something new since PFP 2008, just on this web site. That's why there's some hope that a better term could be found before it gets published elsewhere.

by nat (not verified) :: Fri, 07/18/2008 - 7:39am

There's no "truth" in PFP 2008, which saves me the price of a Sharpie. Go ahead and buy one.

by GlennW (not verified) :: Fri, 07/18/2008 - 12:32pm

Thanks for the responses. That's what I was getting at-- would I be any further confused by a (non-revised) "True Yards" statistic as presented in PFP 2008 than I already am? And the answer is no...

by Wanker79 (not verified) :: Tue, 07/22/2008 - 3:15pm

My vote goes to Equivalent Yards, abbreviated EqY and pronounce ecky (for the sake of internet short-hand and table headings).

Just because you're trying to come up with a number that is easily relatable/understandable doesn't mean that you can't use high school level vocabulary.

by Wanker79 (not verified) :: Wed, 07/23/2008 - 8:21am

I've changed my mind a little. I think the pronounciation of EqY should be "eckwy", like equity without the 't'.

by cjfarls (not verified) :: Wed, 07/23/2008 - 2:56pm

For my vote, I actually really like "success yards" as mentioned here by Scott C.

2nd best would be Effective Yards or Equivelent yards.

Adjusted yards is better, but does have the confusion problem with "Adjusted-Line Yards".

True Yards is god-awful... please burn that phrase and any reference to it.

by Jim Glass (not verified) :: Tue, 07/29/2008 - 6:20pm

FWIW, not much I know, I'd prefer a measure:

True Points, which reflects how much a player actually contributes to winning games, over

True Yards, which reflects, I dunno, one player verus another -- but how much do X true yards contribute to winning how many games?

Fan familiarity with a stat doesn't help its usefulness. E.g., in baseball "Win Share" reflects how much players contribute to winning games, while "True Batting Average" wouldn't, even though 95% of fans are more familiar with BA.

Of course I know we don't have "true points" either, so this is kind of moot ... I'm just musing aspirationally.