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13 Oct 2005

Too Deep Zone: Breaking the Tackle Code

by Mike Tanier

The 2001 Arizona Cardinals had a very poor defense. They allowed 5,695 offensive yards, the fourth worst figure in the league. They allowed 322 offensive points, ninth worst in the league. Their defensive DVOA of 13.7% was third worst in the NFL (click here for a DVOA explanation).

The middle linebacker for that Cardinals team, Ronald McKinnon, finished sixth in the NFL with 98 tackles. Safety Kwame Lassiter finished second among defensive backs with 83 tackles. Two other linebackers, Rob Fredrickson and Raynoch Thompson, finished among the top 50 linebackers in tackles. In all, Cardinals linebackers recorded 259 tackles, the third highest total in the NFL, while the secondary racked up 343 tackles, second-highest in the NFL.

So how did a lousy defense rack up so many tackles? It turns out that the 2001 Cardinals are just a typical example of the rule, not the exception. Bad teams generally have very good raw tackle stats. Good teams, especially teams with good defenses, produce low tackle totals.

In 2004, the Colts led the NFL in tackles, with 788. They were followed by the Raiders, Seahawks, Saints and Giants. All were below the league average in DVOA, with the Raiders and Saints among the worst defensive teams in the NFL. Three of the best teams in the NFL according to defensive DVOA, the Bills, Broncos, and Steelers, finished 29th, 31st, and 32nd in tackles. The Dolphins, another good defense, ranked 30th. The Redskins ranked 26th.

If DVOA isn't your bag, try a stat like Offensive Points allowed. The results are the same: the top five teams in tackles all allowed an average of over 21 offensive points per game. The four teams at the bottom averaged 18 or fewer points per game. Or just look at the team names: you don't need stats to tell you that the Raiders had a bad defense and the Bills and Steelers had great defenses in 2004.

The trend continues this season. The 49ers, Jets, Rams and Raiders have very high tackle totals. The Redskins and Buccaneers have extremely low totals.

The inverse relationship between tackle totals and quality isn't perfect; statistical relationships rarely are. The Eagles, a team with a good defense, ranked sixth in tackles in 2004. The Chiefs, with as bad a defense as you'll ever see, ranked 27th. Similarly, the Colts have a high tackle total this season, while the Vikings and Texans have relatively low totals.

But perform a simple linear regression (a method to find out if one variable is directly related to another, as explained here) and the trend is evident. As defensive DVOA goes up, tackles go up -- and that's bad, because the higher the DVOA, the worse the defense. The "r" value is about .375, the sign of a definite (but not absolute) relationship. Use offensive points allowed or some other relevant stat in place of DVOA and you get comparable results.

So face it: if the starters on your favorite team, particularly the linebackers and defensive backs, have high tackle totals, it's probably a sign that the defense isn't very good.

Reverse Logic

At first, the relationship between tackles and defensive quality seems counter-intuitive. But the more you think about it, the more sense it makes.

For defensive players to make tackles, what has to happen? Obviously, the other team must execute a play. Furthermore, the play has to end with a tackle. That eliminates touchdowns, interceptions, incomplete passes, and plays where the back or receiver steps out of bounds without being forced. In other words, most tackles come at the end of either a) handoffs or b) completed passes.

So clearly, bad defenses have an advantage. Opponents can run more plays against them, because they can't stop drives as well as good defenses can. Because bad defenses cannot stop the pass, opponents can complete more passes against them. Because bad defenses usually belong to bad teams, opponents often have the lead, meaning more handoffs to eat the clock, and more effort on the part of the offense to stay in bounds.

All of which means one thing: more opportunities to make tackles.

There are three effects that act to counter-balance the forces that lead to more tackles for bad defenses:

1. When teams are milking the clock, they often run fewer total plays. This appears to have a very minor effect on tackle totals, one offset by the fact that so many of these slowly-executed plays are handoffs in the middle of the field.

2. Teams with effective quick-strike offenses tend to a) put their defenses on the field more often and b) force opponents to speed up the tempo of their play, resulting in more plays for the opponent and more tackle opportunities. This is why the Eagles had a high tackle total despite a good defense, and why the Colts led the league in tackles despite an average defense in 2004. But this factor is also offset somewhat by the fact that a good defense, even in prevent mode, will force lots of incomplete passes when holding a lead.

3. Defenses that allow lots of big plays will have lower tackle totals because, frankly, they can't tackle anyone. If opponents can go 80 yards in three plays, then the defense will probably only record two tackles. This explains why the Chiefs had a low tackle total in 2004; the Texans are having similar problems this year.

But none of these factors can truly stem the tackle tide. Tackles depend on completed passes and handoffs more than any other variable, and bad teams allow more than their share of both.

Tackle Opportunities

Take a team's handoffs and their completed passes, add them together, and subtract touchdowns. The result is Tackle Opportunities. Tackle Opportunities have a very high correlation with solo defensive tackles: for stat fans out there, the r-value is a healthy .802. The average team gets about 720 Tackle Opportunities and records 700 solo tackles: out-of-bounds plays and other oddities make up the difference (note that players often earn a tackle for forcing a ball carrier out of bounds).

The range of Tackle Opportunities was 603 to 800 in 2004; the Steelers recorded the 603, the Raiders the 800. The 200-unit range in Tackle Opportunities is roughly consistent from year to year. Actual tackles also fall into a relatively neat 200-unit range, and the standard deviations for both are large: 43.6 for Tackle Opportunities, 47.7 for tackles.

What does all of this number crunching mean? It means that bad defenses have about 200 tackles to split up among their defenders that great defenses don't. That comes down to 11 tackles per defensive position, though the tackles aren't really distributed that evenly. And the standard deviation suggests that the difference between a somewhat above average team and a somewhat below average team can amount to 95 tackles: almost nine per starting position.

Think about that in terms of Danny Clark, who had 99 solo tackles for the Raiders in 2004, or Robert Griffith, with 92 solo tackles for the Browns. Or look at the other side of the spectrum: John Lynch's 48 tackles for Denver, James Farrior's 68 tackles for the Steelers.

Powerful forces were distorting these totals, elevating Clark and Griffith, punishing Lynch and Farrior. Those same forces are helping Jonathan Vilma right now. Vilma is a solid player on a decent defense, but the Jets' offense is so bad that Vilma is always on the field. He leads the league with 47 solo tackles. Under other circumstances, Vilma could play at the same level but register far fewer tackles.

Tackles by Level

When you realize that tackles aren't evenly distributed among players, then the forces shaping defensive statistics become even stronger. Only 25% of all tackles are made by defensive linemen, 32% by linebackers, and 43% by defensive backs. Yes, almost half of all tackles are made in the secondary.

If defensive backs make the most tackles, then why are the NFL's tackle leaders always linebackers? It's simple, really. The 221 tackles made by an average team's linebackers are usually split three ways, sometimes four. The 302 secondary tackles are always split at least four ways, with fifth and sixth defensive backs playing so regularly that they eat up a fair percentage of the totals.

You might expect that better defenses make more tackles on the defensive line, while weaker defenses make more tackles in the secondary. That's somewhat true, but there's a lot of noise in the data: 3-4 vs. 4-3 defenses, players who can be classified as either linemen or linebackers, and the effect of a great defense spending the fourth quarter in prevent mode all pollute the data. But there's a slight positive correlation between good defenses and line tackles (gummed up by 3-4 teams like the Steelers) and a significantly stronger negative correlation between defensive quality and secondary tackles. The linebacker data also has a slight negative correlation; since linebackers and DBs make far more tackles than linemen, the result is a fairly firm negative correlation between tackles and quality overall.

Remember that 200 tackle split between the best and worst teams? If 43% of the tackles go to the secondary, that's 86 tackles. You can give 20 to each starter and let the nickelback keep the rest. The linebackers get 64 tackles; in a 4-3, that means another 20 for each starter, plus four for the backups. That leaves 40 for the lineman, but in reality, if the defense is truly bad, those linemen will claim a smaller percentage of the booty, meaning more tackles for the linebackers and DBs.

Those 20-tackle swings separate the best teams from the worst teams, but with high standard deviations, even the difference between decent and mediocre can mean 11 or 12 tackles at positions like middle linebacker or strong safety, tackles gained not on merit but due to circumstance. A dozen tackles is the difference between 12th and 40th on the league leaders list.

If you haven't figured it out yet, it means that tackle totals are almost completely useless for evaluating the performance of individual players. And justifying the quality of your team's defense by saying that "Joe Linebacker is third in the league in tackles" is almost precisely counterproductive.

Good Numbers Gone Bad

So if tackle totals are meaningless, is it possible to come up with a good statistic to measure the performance of an individual defender?

Yes, but it takes a lot of work. With some massaging, we can get a little truth out of tackle totals. Roland Beech's method of breaking down tackles by yardage and situation (which you can find at Beech's Two Minute Warning and in Pro Football Prospectus 2005) shows that some defenders make more significant tackles, while some just clean up the mess after 12-yard gains. Beech's technique makes it easier to single out defensive tackles who make all of their tackles right at the line of scrimmage or expose frauds at weakside linebacker who only make stops downfield.

A quick-and-dirty way to determine a defender's contribution is to take the player's tackles and divide them by the team's tackles. Players like Derrick Brooks and Ray Lewis shine in the "percent of team's tackles" category, showing that high tackle totals don't always come from easy opportunities.

But even these approaches are limited. Beech's methods can't help a linebacker whose front four is so terrible that he's forced to make lots of downfield tackles. Some coaches funnel plays to their top linebackers, inflating their tackle totals and screwing up the team percentages. And cornerbacks present the thorniest problem: if they do their jobs right, they won't have to tackle anyone, because the receivers they cover won't be open.

One major problem lies not with the plays that are counted, but the plays that aren't counted: incomplete passes. Good defenses force a disproportionate amount of incomplete passes when compared to bad defenses. In 2004, opponents executed over 950 plays against the Bills; 201 resulted in incomplete passes, over 21%. Opponents executed over 1,046 plays against the Raiders, but just 186 passes fell incomplete, or under 18%.

Many of those incomplete passes represent good plays by individual defenders: tight coverage in the secondary, good pressure from the front four, or a linebacker blitz that forces a bad throw. These efforts are sometimes counted in hard-to-find categories like "hurries" and "passes defensed," but these stats aren't much help. Hurries can still lead to completions, and the player who breaks up the pass is actually the one guy whose receiver may have appeared to be open: shouldn't his teammates get more credit than he does?

At Football Outsiders, we're always on the prowl for better statistics, and we're eager to break the "tackle code" and create a reliable metric for individual defenders. We've already come up with some useful techniques; for example, we break down DVOA by primary receiver, secondary receiver, slot receivers, and so on. If a team always shuts down their opponents' tight ends, we know about it. By the end of this season, our game charting project will allow us to determine who should get credit for such an accomplishment: the free safety, a linebacker, a nickel defender, or some combination of defenders. Our Adjusted Line Yards statistic can be used to determine whether a team's run defense is stout up the middle, to the left, or to the right. Through game charting, we'll find out who deserves the credit: the linebacker making the plays, the lineman eating the double teams, or someone else.

But while we toil away in the Football Outsiders laboratory, the moral of the story remains simple. Read tackle totals if you want, use them in your fantasy league if you want, but don't use them to compare players. Take several grains of salt before trying to interpret them. And never forget that a high tackle total could be the sign of a great player, but it's more likely to be the result of playing for a lousy team.

(Note: only solo tackles on defensive plays were counted in this study, not assists or special teams tackles.)

Posted by: Mike Tanier on 13 Oct 2005

32 comments, Last at 08 Nov 2005, 4:14pm by Gio Loz

Comments

1
by Brad (not verified) :: Thu, 10/13/2005 - 10:53pm

I've never put too much thought into this particular issue, but you've pointed to some correlations that I instinctively felt, such as the bad defense=high tackle totals because of more opportunities. I think it will be very interesting for you guys to actually figure out how to judge the quality of play of individual defenders. Let's hope those answers aren't as intuitive. :)

2
by Led (not verified) :: Thu, 10/13/2005 - 11:01pm

"if the starters on your favorite team, particularly the linebackers and defensive backs, have high tackle totals, it’s probably a sign that the defense isn’t very good"

You know who the top 5 in tackles were last year? Keith Bulluck (TEN, #23 in DVOA), Donnie Edwards (SD, #11 in DVOA), Ray Lewis (BAL, #2 in DVOA), Zach Thomas (MIA, #9 in DVOA), London Fletcher (BUF, #1 in DVOA). Number 6 is Rodney Harrison, who plays for team that played pretty good on defense too. Number 7 is Derrick Brooks, etc. The fact that bad defenses have more tackles as a team (which makes complete sense) doesn't necessarily translate to individual performances. It's not surprising that the extra tackles for bad defenses get disproportianately distributed to the DB's, who are the ones making the tackle on all those extra completed passes. I'm not saying tackles are the best stat, but it's a decent quick and dirty way to look at 4-3 MLB's. The best 4-3 MLB's, if they play every game, should always be among the leaders in tackles.

3
by Vince (not verified) :: Thu, 10/13/2005 - 11:15pm

This article is gold.

I still feel that the only way to realistically assess defensive players, statistically, is to give to start with the value of each team's defense, and then use individual numbers to determine which players deserve the lion's share of the credit.

4
by mactbone (not verified) :: Fri, 10/14/2005 - 12:14am

I really like the article but I didn't see any mention of one other factor I've seen elsewhere - teams report their own players' tackles. I remember mystery tackles being awarded to players "after reviewing the tape." Not to mention that every team had different definitions of assisted tackles.

Tackles may be an interesting stat to look at, but they shouldn't be one of the most important ways to compare players.

5
by Bruce Dickinson (not verified) :: Fri, 10/14/2005 - 12:20am

i like the word TACKLE. to read it about 100 times in one article was both disturbing and had the effect of a stimulant. but the article was quite interesting. can't wait for you TOO DEEP to TACKLE more subtle issues with the precision of a middle linebacker.

6
by BlueStarDude (not verified) :: Fri, 10/14/2005 - 1:28am

Great stuff. Can't wait to see what FO comes up with.

7
by Israel (not verified) :: Fri, 10/14/2005 - 1:31am

And cornerbacks present the thorniest problem: if they do their jobs right, they won’t have to tackle anyone, because the receivers they cover won’t be open.

Not to mention (which you didn't) cornerbacks who play run defense and blitz.

Also, true as you say that you cannot tell a good player by his many tackles, but surely you can judge many a bad player by his lack of same.

8
by Bruce Dickinson (not verified) :: Fri, 10/14/2005 - 1:41am

re 7.
i'm not sure i agree 100%. some players draw constant double teams and will get no tackles while positional counterparts clean up.

Troy Polamalu doesn't have more sacks than Julius Peppers because he's a better lineman, but because PIT's front seven eat up all the protection so he can get to the QB (and Dick LeBeau loves to blitz him).

9
by Israel (not verified) :: Fri, 10/14/2005 - 1:46am

#8 - I meant that you cannot assume that all tackles made by a defensive back reflect a play that reached the secondary.

Second point, after I read this wonderful piece, I happened to read both the Post-Gazette and the Tribune-Review on Polamalu's game against the Chargers. The two papers gave different stats on the number of tackles Troy made. Is this a "reporting competence" issue, or simply something that is legitimately hard to get right?

10
by Kibbles (not verified) :: Fri, 10/14/2005 - 2:56am

This article is great, and agrees with a lot of arguements I've made to my friends recently. One in particular is trying to convince me that Al Wilson is not an elite MLB, and that he's only had one good season (three pro bowl trips notwithstanding). I've been countering that there's a lot more to being a MLB than getting tackles, and that Denver's defense, and all the others most like it (Indy and TB spring immediately to mind) aren't known for producing a lot of tackles at the MLB position (the WLB tends to get the most, a la Derrick Brooks). And then he says that Al Wilson obviously isn't better than whoever plays MLB in Indy, because he's not getting more tackles, and I respond by saying that every defense is going to get tackles, regardless of how good their players are, so you can't compare players based on tackle totals. I'll be sure to send this article his way and gloat a little.

Re #2: How do you explain Al Wilson, then? Or are you going to try to convince me, too, that he's just an average (or even below-average) MLB, like his tackle numbers suggest?

11
by Vince (not verified) :: Fri, 10/14/2005 - 6:41am

Re#9: That's another thing: The whole process of determining which players get credit for a tackle can be VERY subjective. Inherent team bias aside, two reasonable people could score a game and come up with wildly different tackle numbers.

Something else I thought of: Some people who study baseball say that saves are a meaningless stat, but blown saves reveal a lot. Similarly, I think total tackles may not say mucb, but MISSED tackles will say a lot.

12
by Moe (not verified) :: Fri, 10/14/2005 - 6:50am

This article is why FO is so great.

The "Main Stream Media" isn't even asking these questions - they interfere too much with their "What a warrior! Boom! Smashmouth cover two West Coast narrative"

FO knows that statistics will never tell the whole story, but they certainly tell more of it.

13
by Snagglepuss (not verified) :: Fri, 10/14/2005 - 9:13am

Great article!

Funny thing is, all week I've been reading how good the Jets defense is . . .

14
by MikeT (not verified) :: Fri, 10/14/2005 - 10:25am

#5: I counted 87 uses of "tackle" or "tackles". I tried hard not to overuse the word, but there aren't many good synonyms. Anyway, I think it has a hypnotic, mantra-like effect. Or make it a drinking game!

#2: Last year, the top 5 in tackles were all great players on solid defenses, as you said. Usually, the top 5 or 10 is a mix of true stars like Lewis or Thomas and some Ron McKinnon/Jay Foreman types who are pretty good but had inflated stats. And there are often great linebackers who end up far down on the list because they play on great defenses that force lots of 3-and-outs. But your point about the larger distortions occuring in the secondary is right on, and we shouldn't automatically downgrade MLBs with high tackle totals.

#13: I don't mean to dis Vilma or the Jets defense. He grades out as a very good young player. But like I said, his tackle total has been helped by the amount of time he has been on the field.

#4 and tackle reporting: We get our tackle stats from game logs. Teams keep their own stats, which are often very different. Tackle total reporting is much more standard than it was about 12 years ago. I used to add up tackle totals from USA Today, then discover that my totals and the team totals differed by as many as 50 tackles for some players. There is clearly some subjectivity still, but independent game scorers for the NFL now tabulate the results, so I think the data is pretty reliable.

#7 There are lots and lots of players who have had relatively low tackle totals but were considered great players. Deion Sanders and Leon Lett are two typical examples. Did I just use two Cowboys as examples? Yikes! Well, they were a CB and a DT on a great team. One dealt with double teams, the other shut down half the field, and the fact that they often played on great defenses (with great ball control offenses) further drove down their tackle totals. Or, check out Casey Hampton's stats for a more contemporary player.

15
by Independent George (not verified) :: Fri, 10/14/2005 - 11:33am

Feh. This was all totally obvious to anyone who ever played Madden :)

Seriously, though - great article, Mike. Separating individual performances from team performances is always the hardest part of watching football. The frustrating thing is that we now know with some certainty what a bad statistic is (tackles), but we still don't have a good one to take its place.

16
by Dryden (not verified) :: Fri, 10/14/2005 - 11:43am

#13: No one is saying the Jets defense isn't good, maybe even very good, but if your defense is on the field for 45 minutes a game, it presents a lot of problems...

17
by Jerry P. (not verified) :: Fri, 10/14/2005 - 4:12pm

"The frustrating thing is that we now know with some certainty what a bad statistic is (tackles), but we still don’t have a good one to take its place."

Well that should change. I don't know the details of the game charting project but you should be able to generate a bunch of useful stats that the real teams use.

Vince is right that missed tackles are the key. Just like we know how much of a teams rushing yards come further than 10 yards passed the line of scrimmage, we need to know how much of a teams yards are after missed or broken tackles. Even during tackles.

There's a lot that could be done and we should think about what would be the best way to report these stats. I'd love to see a success rate for tackling as I think most of us would. The discussion needs to be centered around how it's going to be scored. Should down and distance adjustments be made? Does holding a guy up so someone else can make the tackle get partial success? Is there a penalty per yard the ball carrier gets while the tackle is being made? Stuff like that.

18
by Scott de B. (not verified) :: Fri, 10/14/2005 - 4:37pm

If you can allocate Tackle Opportunities to different players, then you can calculate Tackle%. The whole problem is like trying to quantify defense in baseball -- a difficult issue.

19
by Jim A (not verified) :: Fri, 10/14/2005 - 4:56pm

I agree that this is a terrific article.

As others have stated, there's a fair amount of subjectivity when awarding individual tackles. Tallies from NFL.com vary quite a bit from those compiled by Stats Inc. Many teams publish their own totals and those tend to be even more variable, but generally inflated compared to other sources. Which is "most accurate"? One could argue that the NFL or Stats (or FO) have the ability to put procedures in place to maximize consistency across all games. On the other hand, individual teams probably spend more time reviewing each play and are more familiar with its players, arguably resulting in greater accuracy.

Is it even possible to come up with a definition of a tackle that can be used with minimal room for bias or interpretation? Or for a more cynical way of putting it, do incentives exist for teams to skew their tackle totals (consciously or otherwise) away from their most objectively accurate numbers?

20
by Troy (not verified) :: Fri, 10/14/2005 - 5:00pm

Lots and lots of great defensive players who don't have great tackle stats? I've got to say that I disagree. I think there are some, but not as many as the author might assume in order to make his point.

I'm in a fantasy league with individual defensive players. Defenders get points for tackles, assists, INTs, passes defensed, sacks, fumbles forced ... the combination gives a pretty good picture that separates good defenders from bad, I think. But the guys with inflated tackle stats on bad teams aren't all that prevalent. I think there is something here, but not such a huge correlation as promised.

21
by GBS (not verified) :: Fri, 10/14/2005 - 6:15pm

#9.
There are at least two different sets of tackle statistics. The attached link goes to an article that's a couple of years old but covers the subject pretty well.

22
by Terry (not verified) :: Fri, 10/14/2005 - 9:59pm

Anytime there's discussion about tackles, I always think of Zach Thomas and his patented "tackle the RB 8 yards down the field" technique.

23
by Nick (not verified) :: Fri, 10/14/2005 - 10:48pm

A few points:

- On the difference in the numbers, the figures which come from the press-box and play by play accounts are at least consistent as the league gives guidance to ensure consistent application. The team figures will vary widely as different defensive coaches apply their own personal touches to the definition. If you look at the Saints in 1983 the coaches credited both Jim Kovach and Dennis Winston with over 200 tackles a piece - while they certainly had tons of opportunities on that team - those numbers are simply inflated. Also there's suspicion to any team numbers where players have as many or more assists as tackles. The Pats did this in the mid 80's with Clayton Weishuhn and Steve Nelson.

On the analysis, I agree with many points on many accounts, 1.) missed tackles may be more meaningful than tackles made, or at least some ratio of the two, 2.) different schemes certainly funnel tackles differently, not just 3-4 vs. 4-3, but are the DT's playing one-gap or two-gap? Do the ends line up over the tackle, TE, or wide, etc., 3.) on the yardage where tackles are made, yes this is important, but will penalize players occasionally for funny plays. Leonard Little made a great tackle catching a back from 10 yards behind 40 yards downfield last year – it should be applauded, not penalized. Which bring me to the final point, while a tackle downfield is less valuable in that it was more likely to have been made following a first down rather than preventing a first down, isn’t it also more important because it is more likely to have prevented a player from going all the way? How often is Al Wilson or Brian Urlacher the last line of defense, probab;y less so than John Lynch or Mike Brown. Hard to know, and hard to measure.

24
by Nick (not verified) :: Fri, 10/14/2005 - 10:50pm

To Terry's point #23 . . . that's a scheme that, for years, required only that large DT's keep linemen occupied to let Thomas clean the play up. Huge numbers, but they do slightly exagerate his value.

25
by Nathan (not verified) :: Sat, 10/15/2005 - 3:14pm

I was shocked at how many people had never thought of this before.

Also, Bend don't break defenses will have more tackles than not. If you attempt to force more plays per drive, there will be more tackles if you are successful.

I have not looked at stats to back this up, but it'd suprise me otherwise. DVOA vs. Cover 2 teams tackle rating.

Anyone?

26
by Kibbles (not verified) :: Sun, 10/16/2005 - 3:55am

Re #19: I hear that teams tend to inflate the tackle numbers of their star players (i.e. Ray Lewis). To me, this seems extremely counterproductive. If anything, I'd want to DIMINISH the tackle numbers of all my best players, so that when it comes time to pay them, you aren't handing over all the leverage in negotiations on a silver platter. If I were a GM, I REALLY wouldn't want any of my players to finish in the top 10 in the NFL in any positive statistical category other than wins.

Unless, of course, there was a system in place (like Denver's running system) so that I could easily explain away a player's stellar performance when it came time to pay him.

27
by Kibbles (not verified) :: Sun, 10/16/2005 - 4:05am

Thinking about the tackle problem, I think the fundamental problem has to be that all tackles aren't created equal. I mean, we have a special name for all tackles of the QB behind the line of scrimmage, right? We call them "sacks" and not just "tackles". So why don't we further categorize tackles? I can come up with 4 basic types of tackles very easily. First would be unaided tackles, where one defender meets the ballcarrier and brings him all the way to the ground before another defender arrives at the scene. We could call these "tackles". Then we'd have tie-ups, where a defender ties up the ballcarrier and impedes his progress until another defender arrived at the scene and helps bring the ballcarrier down. That leads us to the next type of tackle- the assist, where a defender helps bring down a ballcarrier who is tied up. Finally, we'd have the scrum, which is where a host of defenders (2 or more) all converge on the ballcarrier at the same time and all bring him down in one great big joint effort. You could also include force-outs, which get credited either to the nearest defender when the ballcarrier steps out of bounds (if he goes voluntarily), or the defender who knocked him off-balanced and forced him to step out (if he goes out after contact).

I think the biggest problem facing people charting tackles is just that there are so many kinds and there's really no differentiation between them. Water that falls from the sky is called "precipitation", but could you imagine if weather reports simply said "There'll be precipitation today" without clarify whether it would be rain, snow, sleet, or hail?

I don't know, I don't chart the games, so I'd really like to hear from some of the people who do. Would those definitions be strict enough that it'd be relatively easy to objectively identify just how many of each type a player made? Anyone else have any other suggestions for categories, or ways to further clarify the definitions of each category?

28
by Jerry P. (not verified) :: Sun, 10/16/2005 - 2:14pm

Kibbles, that's what I was trying to get at in #17. I'd really like to know how many yards a team gets after broken tackles. How many yards a team gets while being tackled. Simply making contact after a yard is meaningless if the ball carrier can consistently push for three more before he goes down.

DVOA can't separate which defenses are unsuccessful because they are straight up out of position from the ones that tackle bad. I'd like to see the problem tackled. (<--- haw haw haw)

29
by Jerry P. (not verified) :: Sun, 10/16/2005 - 2:18pm

Aw, I used a less than sign and it cut off my "ha ha ha" at my own pun. Also, fix the freaking time on the web server.

ntpdate -u 0.us.pool.ntp.org

30
by Nathan (not verified) :: Sun, 10/16/2005 - 10:30pm

Also, how many tackles a team misses would be interesting, along with a "Tackle succses percentage" Alot of yards are allowed through missed tackles, and there should be a stat to show that.

::Nathan

31
by Sophandros (not verified) :: Wed, 10/19/2005 - 5:23pm

Kibbles,

The gang tackle that you described and named as a "scrum" is more like a maul, and should be called such. Plus, guys get to say that Team A mauled Player B, my foreign friends will have less to laugh at about gridiron, and I won't go nuts hearing a rugby term abused.

32
by Gio Loz (not verified) :: Tue, 11/08/2005 - 4:14pm

i want to know wholeads the nfl history in tackles, or where can i see a list.I can't find it if you can send me an email with some info it would be great