Writers of Pro Football Prospectus 2008

14 Mar 2011

Keeping the Defense Off the Field

Guest Column by Daniel Lawver

Do Offenses Improve Defensive Performance By Extending Drives?

The home team is down by a touchdown with eight minutes left in the fourth quarter. For the second drive in a row, its offense sputters and punts after a three-and-out. The defense gets back on the field, beaten, broken, and exhausted. If the offense had been able to sustain drives, the defense might have had the energy to prevent the opposing offense from scoring another touchdown, effectively ending the game.

This is a common story told repeatedly by announcers during fourth quarters. If the offense had played better and allowed the defense to rest more, the defense would have played more effectively.

For example, the Arizona Cardinals offense became far less efficient after losing Kurt Warner. Their offensive DVOA plunged from 10% in 2009 to -36% last season. In turn, the offense is running fewer plays per drive, meaning their defense has less time to rest. The Cardinals' defensive DVOA increased from 0% in 2009 to 8% this season. (Recall that a rise in defensive DVOA is a bad thing). So how much of the decline in the Cardinals defense can be explained by the decline in the Arizona offense's ability to extend drives and allow the defense to rest?

We all know the basic conventional wisdom here: Offenses that run more plays per drive should have defenses that rest more and perform better on average. Is it true? We can estimate the effect of the number of plays an offense runs per drive -- and therefore the amount of rest that the defense gets on average between drives -- on defensive performance. To do this, I compare the number of plays that an offense runs per drive to their defense's performance, measured by defensive DVOA.

This is an appropriate exercise for a few key reasons. First, while defensive performance affects the number of plays that an offense runs per game, it is not likely that defensive performance affects the number of plays an offense runs per drive. Second, performance of the defense affects the average starting line of scrimmage for the offense, and therefore potentially affects the number of plays that an offense runs per drive. Defensive performance does affect the average starting line of scrimmage for an offense. However, the average starting position for an offense has a very small effect on the number of plays the offense runs per drive. Over the course of the season, teams that start offensive drives 10 yards closer to the end zone than average run 0.1 fewer plays per drive than average.

One difficulty in doing this exercise is estimating the amount of time that a defense rests per game. Without explicitly measuring the amount of time between drives, there are two potential ways to measure the average amount of time between drives: game time elapsed per offensive drive and number of plays per offensive drive. In this article, I use the number of plays per drive as a measure of the amount of time that the defense rests between drives. Defensive rest, of course, depends of the actual amount of time that elapses between drives, rather than the amount of game time that elapses between drives. My best guess is that the number of offensive plays per drive is a better measure of the amount of time between drives. Regardless, my results do not change if I use game time elapsed per drive instead.

In Figure 1, I plot the relationship between offensive plays per drive and defensive DVOA for all teams between the 2003 and 2009 seasons. If there were a strong relationship between these variables, we would expect to see some correlation. It's clear that we don't. Teams at all levels of defense DVOA have a wide range in the number of plays that their offenses run per drive. There is no strong relationship between the amount of time a defense gets to rest between drives and its performance.

To determine the impact of the number of plays an offense runs per drive, I look at the relationship between offensive plays per drive and defensive DVOA. In Figure 2, I plot this data along with the line that fits the data best. These results actually suggest that an increase in the amount of time the defense gets to rest per drive slightly worsens the performance of the defense. If an offense runs one extra play per drive over the course of a season, we can expect an increase in defensive DVOA by about two percent (once again, meaning a decline in defensive performance).

This estimate, however, is not statistically significant. This means that it is reasonable to believe that the number of plays an offense runs per drive has no impact on defensive DVOA. The amount of time that the defense gets to rest per drive is a very unimportant determinant of defensive performance. Similar results are seen when doing this exercise using data on the performance of the pass and rush defense.

Let's return briefly to the recent decline of the performance of the Cardinals. These results suggest that the decline in the offense's ability to extend drives has not had a strong effect on the performance of the defense. Other factors, especially the loss of Karlos Dansby to free agency in the offseason, have likely played a much larger role.

One shortcoming of this analysis is that I estimate the impact of the amount of time the defense rests per drive on the performance of the defense over the course of the entire game. One might expect that this has the biggest impact on performance during the fourth quarter. I understand this view, but I doubt that the effect is much bigger in the fourth quarter than it is overall. Defensive DVOA measures the performance of the defense over the entire game. If there were a large effect on defensive performance in the fourth quarter, we would see some effect on defensive performance overall.

One important thing that I want to emphasize is that all of this analysis focuses on defensive performance on a per-play basis, as DVOA is a measure of per-play performance. The performance of an offense does have important effects on the performance of a defense over the course of a game or over the course of a season. The number of plays that an offense runs per drive affects the number of plays that the opposing offense runs per game. As a result, an increase in the number of plays that an offense runs per drive will lead opposing offenses to score fewer points per game because they will run fewer plays each game.

Conventional wisdom holds that offenses affect the performance of their defense through their ability to extend drives, and allow the defense additional time to rest. This conventional wisdom does not seem to be supported by the data. As shown here, the number of plays an offense runs per drive has very little impact on the performance of the defense. One simple explanation for this result is that a team's defensive players aren't the only ones that rest while their offense drives down the field. The opposing offense gets to rest too. The net impact, as shown here, is negligible.

Daniel Lawver is a PhD student in Economics at Arizona State University. You can contact him at dafrk3in-at-gmail.com or at this website. If you have a guest column, something that takes an unconventional look at the NFL or college football, you can submit your idea or rough draft at mailbag-at-footballoutsiders.com. The offseason is a great time to submit a guest column.

Posted by: Guest on 14 Mar 2011

56 comments, Last at 29 Mar 2011, 6:49pm by Cyrus2

Comments

1
by Stat Guy (not verified) :: Mon, 03/14/2011 - 1:04pm

Not statistically significant? Let's see some t-statistics and P-values.

2
by dmb :: Mon, 03/14/2011 - 1:13pm

Given the looks of that scatterplot, I would be shocked if there was any significance even with a very generous threshold of, say, p<0.10. Furthermore, even if there was statistical significance (highly unlikely), there's also the matter of practical significance; check out the microscopic R^2.

Thanks for the guest column; this was a topic I was quite interested in, having debated it a bit here earlier this year.

5
by BenS (not verified) :: Mon, 03/14/2011 - 1:36pm

Agree with dmb, r^2 would be tiny.

But as an additional point to Stat Guy, this data would not yield t-statistics. It's a correlation; thus it would be a Pearson's r value rather than a t-test.

I wouldn't mind seeing the r and p values though.

29
by Ogre (not verified) :: Tue, 03/15/2011 - 10:00am

NERDS!

34
by dafrk3in :: Tue, 03/15/2011 - 11:57am

Thanks for the comments. I'm happy to make the data available to anyone that wants it after I get back from vacation in a few days, and you can calculate any stats you think might be interesting. Feel free to send me an email if you're interested.

3
by TS (not verified) :: Mon, 03/14/2011 - 1:17pm

Nice work, Dan. Now get back to finishing your dissertation.

4
by drobviousso :: Mon, 03/14/2011 - 1:31pm

Well written piece that makes the best of an imperfect data set.

The home team is down by a touchdown with eight minutes left in the fourth quarter. For the second drive in a row, its offense sputters and punts after a three-and-out. The defense gets back on the field, beaten, broken, and exhausted. If the offense had been able to sustain drives, the defense might have had the energy to prevent the opposing offense from scoring another touchdown, effectively ending the game.

While that's the narrative that's usually used, it sounds more like the defense is going to be facing some very short fields. By their nature, will result in more scores against, no matter what condition the defense is in.

6
by Andy Watkins (not verified) :: Mon, 03/14/2011 - 1:59pm

I'm concerned that we've failed to control for a factor. Teams have limited spending money and talent-attracting-ability. Only elite teams have good defenses and good offenses. There may be a counter-trend, to whatever limited extent that the better your defense, the worse your offense, for the sheer reason that most teams couldn't afford offering awesome contracts in both areas.

52
by Stevo (not verified) :: Thu, 03/17/2011 - 12:28pm

This is a good point.

Another factor that needs to be controlled is situation. A team with a poor offense will find itself frequently trailing, with the other team's offense taking a more conservative approach. This would give an apparent boost to the trailing teams's defensive DVOA. On the flip side, a good offense will face a more desperate opposition opening it up a little more to stay in the game.

The true effect of tired defenses may be subtly positively correlated, but team composition and situational adjustment by the opponent may wash these out or give a false apparent negative correlation.

56
by Cyrus2 (not verified) :: Tue, 03/29/2011 - 6:49pm

I agree about the issue. It is a glaring issue, in my mind. The way this data was used does not account for this-- it seems clear to me that a better offense usually indicates more of an offensive focus, meaning the defense will have less of a focus.

What I would like done is to compare each team on a year by year basis. For example:
2009 Cardinals, X1 Offensive Y1 Defensive
2010 Cardinals, X2 Offensive Y2 Defensive

Look first at the difference in offensive (X2-X1), and then see if there is a corresponding difference in defensive (Y2-Y1).

This won't correct for drastic changes in personnel, but does seem like a better baseline as you are comparing two similar datapoints to see if there is a trend.

7
by Karl Cuba :: Mon, 03/14/2011 - 2:13pm

Is it possible to compare DVOA of defenses that have run more than a certain number of plays? Say compare the DVOA of teams before and after the 50 play threshold.

The data set would be smaller but you would be looking more directly at the issue. (Maybe, I think. My statistics classes were more than a decade ago.)

Good article though.

54
by panthersnbraves :: Fri, 03/18/2011 - 11:07am

That is where my thoughts were headed.

8
by JonFrum :: Mon, 03/14/2011 - 2:16pm

I've never understood why defenses get more tired the longer they're on the field, but the offenses purr right along. Is it really more tiring to play defense? Has it been demonstrated?

10
by Mort (not verified) :: Mon, 03/14/2011 - 2:49pm

Anecdotally: yes.

At least in sports where you play both offense and defense, it's more exhausting to play (man) defense. I think it's a function of knowing what is happening next. When you make a cut, you know what direction you're going to go out of your cut while your defender doesn't. As a defender you have to be on your toes more and react faster and that's difficult to sustain. Good defense has to be in some sense more frantic and thus takes more energy.

I'm not sure how well that translates to football where you only ever play offense or defense (which affects how you condition/are conditioned) and where lots of zone and zone-like schemes are used.

11
by SFC B (not verified) :: Mon, 03/14/2011 - 2:54pm

I think the "why" would be that the offense gets to set the pace. They determine when the ball is snapped, where it is going, etc.

Also, from what I have seen the defense, particulary the D-line, tends to have bigger guys who are always having to fight through the O-Line and usually must make an effort to get to the ball-carrier. Sefenseive linemen have to get to the QB or RB to be successful (over simplification, I know), the offensive linemen can usually succeed by pushing the defensive guy away from that one specific area. In the secondary the CBs and Safeties can't take the play off. They don't know if the receiver they're covering or the zone they're in will be targetted. And they're usually having to defend against people who are physically bigger than they are.

Of course this is all a discussion about fatigue in a population of people who would smoke me all day, every day, in almost any physical or endurance competition. So what do I know?

17
by Aaron Brooks' Good Twin (not verified) :: Mon, 03/14/2011 - 4:41pm

Randy Moss, the WR, can take 50% of plays off on offense and still be in the HOF.

Randy Moss, the DB, can take 50% of plays off on defense, and never make varsity in high school.

21
by sundown (not verified) :: Mon, 03/14/2011 - 5:33pm

The offense knows where the play is going and knows exactly what it will entail. Meanwhile, there's ton of energy expended needlessly on defense. Not that they know it's needless at the time, but you've got to be prepared for every single play to come your way even though that's not going to happen.

Also, throwing blocks tends to require less effort than fighting them off--shielding a guy from the play can be as effective as pancaking him--and pass rushers must constantly try to beat the blocker because every other outcome is a win for the offense.

32
by bravehoptoad :: Tue, 03/15/2011 - 11:30am

I know this is the justification for why defenses wear down more than offenses, but it's apparently not true. (See data above.)

So, we need a new justification for why defenses DON'T get tired faster than offenses. Maybe football is just too stop-and-start for this kind of fatigue to matter.

By the way, these are exactly the kind of articles I hope FO runs during the lockout. A good stats site isn't dependent on news the way other sports sites are, not when there are just so many cool questions to figure out like this one.

38
by dmb :: Tue, 03/15/2011 - 5:37pm

"By the way, these are exactly the kind of articles I hope FO runs during the lockout. A good stats site isn't dependent on news the way other sports sites are, not when there are just so many cool questions to figure out like this one."

Agreed.

55
by Kibbles :: Sun, 03/20/2011 - 4:43am

My first guess would be more liberal use of substitutions on the line. Defensive linemen who see more than 75% of their team's snaps are iron men. Offensive linemen who see fewer than 95% of their teams snaps (when healthy) are unheard of.

25
by Theo :: Tue, 03/15/2011 - 4:38am

Next time the Tuskers play the Locomotives, and Tuskers run a sweep and the play has ended; count the Locomotive jerseys around the ball versus the Tuskers jerseys.

40
by Noah of Arkadia :: Tue, 03/15/2011 - 10:39pm

What our high-school coach used to tell us is that it's more tiring to take a hit than to give it, which means that RBs get very tired, but the OL gets less tired than the DL and LBs.

42
by Noah of Arkadia :: Tue, 03/15/2011 - 10:53pm

In any case, I think the fact that DL substitute all the time while OL never do is a clear indication that playing DL is way more tiring than playing OL.

49
by greybeard :: Wed, 03/16/2011 - 7:25pm

It could also mean that goof OL play requires a lot more coordination whereas DL play can be more individual effort.
Most defenses have 1st down and 3rd down packages, they put better run stoppers on first downs and better pass rushers on the "long" downs. I don't believe team change their OL players frequently.
Or it could be both.

9
by Dean :: Mon, 03/14/2011 - 2:45pm

"One might expect that this has the biggest impact on performance during the fourth quarter. I understand this view, but I doubt that the effect is much bigger in the fourth quarter than it is overall."

This is exactly what I was thinking in the first couple paragraphs. I wish you'd gone into further detail here instead of just dismissing it offhand. It may be that your results would confirm your hypothesis. If so, good, more conventional wisdom debunked. But I think that assuming that 25% of the data would automatically not be overshadowed by 75% sells the story just a little bit short. I'd love to see that data rather than just accepting your assumption.

Otherwise, it's great stuff.

14
by wr (not verified) :: Mon, 03/14/2011 - 3:37pm

Agreed. It would be interesting to (if the data allows) do a quarter by quarter breakdown, and see if there is a noticeable dropoff in defensive DVOA in the 4th
quarter w.r.t. number of offensive plays.

15
by zenbitz :: Mon, 03/14/2011 - 3:53pm

Actually I think the "tired in the 4th quarter" hypothesis could easily be dismissed. Do teams generally have a worse Defensive DVOA in the 4th quarter? I don't think so. But they are ALWAYS more tired in the 4th quarter (even though they are being compared to other 4th Quarter defenses).

I think that we imagine defensive dvoa gradually sloping upward as the game goes on, but I would be that this is not the case. But I don't have access to q-by-q stats, so ...

I suppose there *could* be some kind of "shelf" effect at 90 plays or something, when all of a sudden, the defense breaks down.

12
by Anonymous Coward (not verified) :: Mon, 03/14/2011 - 3:15pm

Wait so are you comparing a team's performance against their own performance when the offense is doing better?

Or were you just checking if teams that run longer drives have better or worse defenses than average teams without accounting for anything else?

13
by tuluse :: Mon, 03/14/2011 - 3:35pm

I have a problem with this article, it doesn't account for differing defensive strengths. I don't think anyone is suggesting that extra rest makes bad defenses good. Just that it allows the defense to play (closer) to it's peak potential. I'd think you would have to look at the same defense at different rates of offensive plays per drive and see how it does.

16
by Kal :: Mon, 03/14/2011 - 3:54pm

One of the things I did last season was plot how a defense declined when facing the Oregon offense and noted that when Oregon was able to run 50 plays by around the second half, they started becoming significantly more explosive. My gut suspicion is that the time that a defense gets to 'rest' isn't significant compared to how hard they do end up working when they're on the field, especially in the NFL with TV timeouts, no real hurry up offenses and generous substitution policies.

I'd be curious if there was any statistical correlation being able to be seen given number of plays run by the opposing offense and defensive performance.

43
by Bobman :: Wed, 03/16/2011 - 1:19am

Most teams who played Oregon this year would say they have empirical evidence. Along the lines of, "We kept it close in the first half, but they were running us ragged, and by the end of the third quarter, we were gassed. Then they scored 21 in the 4th."

So clearly there are some cases in which this holds water, but with those scatterplots above, I'd say it's heavily context-dependent and not consistent. Maybe a nimble OL and a nimble cover-2 D offset each other, but a behemoth OL would wear down a smaller D? And a nimble OL would have less effect on a mammoth DL?

47
by Jimmy :: Wed, 03/16/2011 - 12:56pm

I remember sending Aaron a question about a '50 play rule' that I heard a commentator talking about, saying that defensive coordinators expect their defense's performance to drop off a cliff after that point. Aaron pointed out that the number of plays the defense faces isn't in the NFL's play by play and couldn't be used with DVOA (or at least you would need to have that information charted). I do think that the number of plays is probably the best way to measure this effect. If you were looking at how tired a baseball pitcher was getting you would look at pitches thrown rather than how quickly they threw their pitches or how long they rested for. Intense explosive movements take energy out of the muscles (or build up lactic acid or whatever) and it isn't the time during which the effort is expended that counts but the amount of effort the muscles produce. Of course QBs don't routinely expend similar amounts of energy (especially pocket passers) which could explain why they are able to shred defenses late in games.

Also kudos on your research project. I do find it interesting that your data indicated a similar point at which the defenses began to struggle as the commentator said defensive coordinators expect.

50
by Kal :: Wed, 03/16/2011 - 10:54pm

Thanks.

What was interesting was that I heard about the 50-play rule after I did the work and saw it, and then Chip Kelly mentioned it too. It's something distinctly planned for.

Note also that when Oregon didn't hit the 50+ plays until late in the game there was no real correlation between number of plays and offensive ability. We saw this in every game that Oregon struggled in - Arizona State, Cal and to a lesser degree Auburn all showcased this. Every other game where they hit that 50-play mark early (and often they were behind or not doing well up until that point) they really broke away.

My gut feeling is that there's going to be a stronger correlation not only between number of plays but the type of plays run. I suspect a running play would tire out a defense more than a passing play would, both because the passing plays have more time between plays and because the defense isn't getting punched in the face as much. But it's hard to say; very few teams play at the hurry up level of offense the entire game, there are a lot of factors involved in how tired a team gets (altitude, weather, humidity, time between plays, involvement in the play, rotations) that make it hard to find a reasonable correlation, etc.

But as a rule of thumb it rocked; I knew almost instantly when the Ducks would come back and start kicking Husky ass, for instance ;)

18
by Aaron Brooks' Good Twin (not verified) :: Mon, 03/14/2011 - 4:45pm

First, while defensive performance affects the number of plays that an offense runs per game, it is not likely that defensive performance affects the number of plays an offense runs per drive. Second, performance of the defense affects the average starting line of scrimmage for the offense, and therefore the number of plays that an offense runs per drive.

Huh?

24
by tuluse :: Tue, 03/15/2011 - 2:19am

I'm pretty sure he means for the same team.

31
by Aaron Brooks' Good Twin (not verified) :: Tue, 03/15/2011 - 11:29am

They are still mutually contradictory statements.

33
by dafrk3in :: Tue, 03/15/2011 - 11:55am

The reason you're confused is that it's a typo. It should be something along these lines:

Second, performance of the defense affects the average starting line of scrimmage for the offense, and therefore POTENTIALLY AFFECTS the number of plays that an offense runs per drive.

The next two sentences explain why defensive performance does not affect the number of plays an offense runs per drive. Sorry for the confusion.

19
by dcaslin :: Mon, 03/14/2011 - 4:45pm

I have both anecdotal and design issues with this piece. Anecdotally, watch the 2011 Ravens-Texans game and watch Jarrett Johnson basically fall over with exhaustion while plodding after the QB and you'll know what I mean.

From a design standpoint, I think you're looking at the wrong thing. You should see if teams with shorter offensive drives (or more defensive snaps, or both) have a greater DVOA differential between the 1st Quarter (or first half, or first 3 quarters) and the 4th Quarter. You might even need to factor in age, and/or number of defensive linemen in the rotation, but you could definitely see it happen in Ravens games this year. Perhaps that was an isolated event and not a greater trend, but it was definitely there.

22
by Jerry :: Mon, 03/14/2011 - 6:26pm

If you run those numbers, please let us know the results.

27
by dcaslin :: Tue, 03/15/2011 - 9:27am

I prefer to just complain about others stuff =)

48
by tonic889 (not verified) :: Wed, 03/16/2011 - 1:25pm

Wasn't just the Ravens game vs. Houston. Ravens had a major problem with this all season. See also their loss to New England, playoff loss to Pittsburgh, narrow escape in OT vs. Buffalo. Personally, I think the Ravens spent too much time rushing 3 and not enough rushing 5. Sometimes it worked but when it failed it failed tremendously.

28
by Rivers McCown :: Tue, 03/15/2011 - 9:29am

As the person who charted that game, allow me to point out that while the Ravens defense was supposedly gasping for air, they also pressured Matt Schaub on nine of his last fourteen dropbacks.

30
by tuluse :: Tue, 03/15/2011 - 10:15am

Wasn't the unit with the least depth on the ravens their secondary? So it makes sense they could keep their front 7 rested, but the secondary would tire out faster. Of course the secondary was also probably a lot less talented overall than the front 7, so it also makes sense they would be the wreak link regardless of rest.

36
by dcaslin :: Tue, 03/15/2011 - 2:33pm

Tuluse, as I recall, the Ravens made some suspect roster decisions before that game. They sat most of their extra DL's in order to have better special teams coverage, so they were very thin there. As I recall they also just didn't sub out their DL starters as much as probably should have made sense, either b/c of timing issues in game or b/c they didn't trust the backups.

Rivers, that's a good point. I think almost all of those plays were shotgun snaps that ended in completions though. It was like as long as Schaub could scramble at a moderate pace, he had as long as he needed to make a play. I will attempt restrain my human tendencies to make too much of the anecdotal part though.

20
by Aaron Brooks' Good Twin (not verified) :: Mon, 03/14/2011 - 4:47pm

More fundamentally, all we've really shown is that DVOA doesn't correlate to offensive plays per drive. The underlying premise, though, is rest time. We have no analysis of whether offensive plays per drive correlates with elapsed time.

As an example, Indy runs 5 plays in a far different amount of elapsed time than San Francisco does.

23
by Ed Schoenfeld (not verified) :: Mon, 03/14/2011 - 7:29pm

I'm with Aaron Brook's Good Twin and dcaslin. This study is a nice start at something, but it doesn't really measure what is usually meant by the cliche that defenses get tired later in games.

The other two posts cover most of my reservations, but I'll some more:

First, I wonder how well plays per drive can really measure the sort of offensive dominance that results in a "tired defense" -- offenses can run as many as 15 quick passing plays in a 'football minute.' Not only would a sequence of such plays fail to tire the defense, it might even give the defense some emotional strength as they get to slam receivers running short routes over and over again. But a series of 4 or 5 hard-nosed running plays, or passes in which the QB escapes to extend the play (and the time the pass rushers spend chasing) could blow the wind out of most defensive players.

Second, it seems to me that the proverbial situation almost always has some element of the offense beating the cr*p out of the defense in the old-fashioned smash mouth way.

It might be that the change in design these considerations suggest (Time of possession, time per play, actual time vs. football time, run vs. pass frequency, etc.) will force the ivestigation of data that is too picky to make semse of. But from what see presented right now, I'm not willign to draw a conclusion either way.

26
by Jay Jesse (not verified) :: Tue, 03/15/2011 - 8:23am

"First, while defensive performance affects the number of plays that an offense runs per game, it is not likely that defensive performance affects the number of plays an offense runs per drive."

Unless you're just assuming the results of your analysis I don't see why not. It's just the flip side of the "defense gets tired argument." The better your defense the fewer plays the opponent's team offense runs, meaning their defense is more tired when they get on the field.

Anyway, somebody mentioned above the obvious counter to this analysis, which is that teams that have above average offenses are going to tend to have below average defenses given the salary cap and limited resources teams can devote to their team.

35
by Sha-blam-o (not verified) :: Tue, 03/15/2011 - 12:06pm

I think there may be a bit of a flaw when considering what is to be measured. Instead of looking at simple statistics that measure time of possession and number of plays, actually do the hard work of measuring the amount of time for each individual play. Most plays aren't that long whatsover. In fact, from snap to whistle/tocuhdown/out of bounds etc for most plays is very very short... a long play might last 8 seconds in normative play. Special teams is a little different but it depends on the special team play, a kickoff play is probably longer than a field goal attempt obviously. Regardless, the measure of how many seconds a defense is actually doing work in a play should be utilized instead of simple math with bad measurements.

When you add up the total amount of plays on Defense in seconds of time you'll begin to wonder if anyone really can get tired for only 6-8 min of actual real hard physical exertion/work a game. Imagine, millions of dollars for 8 minutes of work a week (8 min is generous for one side of the ball). Then think, wow, 12-14... maybe 16 minutes of actual play that takes 3-4 hours to watch. Big implications here. Regardless, I think this study should have really considered how much work actually can be compacted into a 6 second play... and why it really just doesn't matter because there aren't enough of them for very long. DO I see an argument for more than 18 games a season?!?!

With that criticism of the measurement used I would say that we'd probably get similar results debunking "conventional wisdom."

37
by Aaron Brooks' Good Twin (not verified) :: Tue, 03/15/2011 - 5:15pm

Usain Bolt makes around $250,000 for 9.6 seconds worth of work. Extrapolated to 6 minutes, that's 9.4 million dollars per equivalent NFL game, and, much like Deion Sanders, he's not required to actually hit anyone.

8 minutes is a long time when you're performing at the equivalent of a sprint. If it weren't, the record 3k would be 4:48, instead of 7:21.

41
by Noah of Arkadia :: Tue, 03/15/2011 - 10:51pm

Especially considering NFL players can't pace themselves. They need to give their all every play.

44
by Bobman :: Wed, 03/16/2011 - 1:26am

Both mentally and physically. On D, you are often reactionary (more so than on O) and so if you are a LB with an assignment, you have to track three potential blockers, a couple potential receivers, a runner or two, and then give 100% for about 10 seconds without making any major mistakes. You have about 15-20 seconds to get settled in case of a quick snap, and then stand in ready position, tensed and doing it all over again before your next 10-second burst of everything.

Guys who dog it or walk between snaps or don't bring total mental focus can rest a bit, but they are known as D-II second-stringers. To make it this far, these guys have to press pretty damn hard, nearly constantly. I don't think Olympic sprinters are using much mental energy. Longer distance races, yes, there is strategy, though nowhere near as complex as playing NFL defense.

39
by David C (not verified) :: Tue, 03/15/2011 - 10:30pm

As others have mentioned, nobody cares how resting affects performance in the first half since of course there is going to be little correlation. It's the fourth quarter that matters, and the fact is that the offense scores more in the fourth quarter than in the first because the offense doesn't have to work as hard as the defense on each play.

46
by Karl Cuba :: Wed, 03/16/2011 - 11:02am

i think that late game scoring has more factors than tiring defenses. I can remember two examples (vs the niners and Bears) I noticed from this season where the Falcons offense was able t move the ball early in the game but it resulted in Ryan getting hit a lot. So they dialed back the offense, keeping more protection in for Ryan and running routes aimed at getting open faster, resulting in Atlanta struggling to move the ball. As the game approached the final couple of possessions the Falcons needed to move the ball and went back to the original scheme meaning that Ryan got hit more but was able to move the ball to gain the needed points. The playcalling changed due to the necessity of the circumstances, they were willing to take more chances at the end of the game.

45
by Joe McKenna (not verified) :: Wed, 03/16/2011 - 10:54am

Yea, I never bought into the whole rested defense makes a big difference in improved D play. But I think a good defense that can help give the team a lead makes a huge difference in allowing the offense to play well. Got any stats on that?

51
by SunshinePacker :: Thu, 03/17/2011 - 9:58am

Honestly, this is one of those studies where you have to step back from the statistics and see if the results actually make sense. I can clearly remember games where the Bucs Cover-2 defense was exhausted after the other team ran 70+ plays. Defensive players have to react to the offense, therefore they expend more energy on a given down than the offense; so the offense resting at the same time the defense rests isn't a 1:1 ratio.

53
by Packer Pete (not verified) :: Thu, 03/17/2011 - 1:20pm

If you've ever sat in the stands in Lambeau in December or January, you'll know that the defense gets plenty of opportunities to rest during those endless TV timeouts and halftime. With the constant subpackages swapping players, few front 7 defenders play the entire game. Zone defenses limit the amount of continuous sprinting by DBs. I've never bought into the tired defense theme. Perhaps later in the game, the offensive coordinator has set up his offensive scheme, the offensive players have found a rhythm.

to the lesser team's offense against the better team's defense?