Tuesday, November 1, 2011

Peyton Manning - Colts Defensive MVP??

by Steven Buzzard

A growing sentiment that has started to crop up with a lot of the talking heads in the league is that the Colts would be pretty terrible if Peyton Manning was playing because the defense has been so atrocious. These same people love to state the obvious and point out that Peyton Manning doesn’t make tackles. However, a lot of stats analysts have known over the years that the Colts offense has actually helped the Colts defense in 3 key ways.

1) They stay on the field a long time and limit the total number of drives per game
2) By staying on the field they give the defense great field position despite terrible special teams
3) By getting leads the defense can force more turnovers

So approximately how much of the collapse of the defense can be attributable to the defense collapsing and how much to the offense collapsing? Since 2003 the Colts have allowed approximately 20 points per game. This year they are allowing 31.5 for an increase of 11.5. Also note that this year league wide scoring is at a record pace and is trending at about 1.1 points over historical averages. These changes are due to a variety of things such as increased passing efficiency, increased passing attempts, changes on kickoff rules, etc. This is very important and is something we will keep in mind throughout the evaluation.

By failing to stay on the field the Colts offense has extended the game fairly substantially. Since 2003 the defense has faced approximately 10.3 drives per game. So far through 8 games the Colts defense has had to defend against 11.1 drives per game. Additionally due to league wide changes there has actually been a decrease in total drives this year of 0.65. So the Colts defense has seen an increase of 0.82 drives per game when they would have expected to see .65 less for a net effect of 1.47 more drives per game. At their current clip of 34.7 yards per drive these additional 1.47 drives per game has been worth 51 additional yards per game. If we use an approximate 12.5 yards per point that is an approximate impact of 4.1 points per game.

In addition to the additional drives per game the defense starting line of scrimmage has also declined as anticipated. From 2003 through 2010 the Colts defense had an average starting field position of 29.5. This year they have faced an average starting position of 31.65 for an increase of 2.15 yards. Additionally, due to changes to the kickoff rules the actual league wide starting position has decreased by 1.85 yards. So essentially the Colts defense is facing 2.15 yards of worse field position where as the league average is facing 1.85 yards better putting the Colts defense at 4.0 yards worse per drive than we would have expected for an average historical Colts defense. Over 89 drives that is equivalent to 357 yards or 28.5 points and a 3.6 per game clip.

The one thing that many people will recognize about the Colts defense is that they are “built to play with the lead”. This essentially gives them the chance to send their star DE’s after the QB creating strip sacks, force bad throws early, and creating turnovers. We can see this clearly in the numbers as well. With the Colts not building leads they aren’t creating turnovers. Historically the Colts defense has forced 1.7 TO’s game compared to 0.9 thus far this year. Many websites have approximated the value of a turnover at somewhere between 40-45 yards. For simplicity’s sake let’s calculate the value of a turnover as 45 yards. In this example, the lack of turnovers is costing the Colts 38 yards per game or 3.0 points. Clearly part of the value of the turnover is better field position for the offense and not just less points allowed by the defense but it is still an impact to the final point differential at the end of the day. Additionally, this entire decrease can’t be attributable to the offense the way the first two items can be but certainly some percentage of it can be. Even if an amount as small as 50% is due to playing with a lead the lack of turnovers may end up affecting the total points allowed by at least 1 point per game.

Now that we have seen that the defense is giving up approximately 7-10 points more per game due solely to the collapse of the offense we can see how much of the collapse can be directly attributable to the defense. Again we will start with yards per drive as our basis to keep things consistent. Historically the Colts have allowed about 30.8 yards per drive vs 34.7 that they are allowing this year for a change of about 3.9 yards. Offenses on average are getting 1.1 yards per drive more than historical averages meaning the Colts defense is playing 2.8 yards per drive worse per game than would be expected. This equates out to about 20 yards per game and 2.5 points per game directly attributable to the defense.

The current year Colts team is giving up about 11.5 points per game more than they have historically given up. Based on some basic analysis it appears that approximately 7-10 of those points are because the offense is not helping them out as much as they have in the past and about 2.5 of those points are due to the defense just underperforming. While 2.5 points per game is a fairly significant decline in defensive performance it isn’t unprecedented, in fact the standard deviation in points allowed by the Colts is 3 points per game and has underperformed historical averages by 2.5 twice in 9 years. The thing that is unprecedented is the number of drives, field position, and TO rates all of which are at all time extremes. Clearly these aren’t the only aspects that go into total points allowed but it is a significant portion. At the end of the day maybe Peyton Manning was the most valuable player on the Colts defense even if he wasn’t and never will be making tackles.

4 comments:

Mike B said...

Another way to look at this is through WPA and EPA. Points allowed will definitely be skewed by how well the offense does, but EPA and WPA should not.

If Painter goes three and out from the 20 and the opposing team gets the ball on their 45 after a punt, that starting field position already has a positive EPA built in for the Colts opponent. EPA and WPA for the defense only measures how well the defense did based on what they were given.

Using Brian's Advanced Team Stats page, I looked at the Colts' defense EPA/P and WPA/G going back to 2008 (positive numbers are bad for a defense):

Year EPA/P WPA/G
2008 0.04 0.02
2009 0.03 0.03
2010 0.06 0.05
2011 0.14 0.21

Based on those numbers, I would argue that the Colts' defense is performing significantly worse this year, and that you can't lay it at the feet of the offense.

Buzz said...

Mike,

Thanks for your response. I think we are saying a lot of the same thing. Like I mentioned the defense is clearly playing worse this year than in previous years, it just wasn’t unprecedentedly worse like the field position, lack of turnovers, and number of drives worse. Based on EPA/P this is their worse season going back to 2003 but a good portion of that difference is due to the lack of turnovers. The lack of turnovers this year compared to previous years is contributing about .05 more EPA/P. How much of this EPA/P is attributable to not having leads and being able to force QB’s into mistakes is debatable but I would guess it would be at least half of it.

Additionally, you can calculate about how many points you would expect the defense to give up every year based on their EPA/P and compare that to their actual points given up. The difference could approximately be things like starting field position, number of drives, points off turnovers, etc. Of course that isn’t exactly what EPA/P is designed for but it could give a good approximation. Let’s start by looking at 2011. The league average points allowed is 22.5 and the Colts are giving up 0.14 points per play more than average. Based on a league average plays of 64 you would expect that they would give up 31.5 points, exactly what they are giving up. What if we did the exact same calculation for every year.
Year Actual Pts allowed Expected Pts allowed Difference
2011 31.5 31.5 0.0
2010 22.0 24.3 (1.6)
2009 19.2 23.4 (4.2)
2008 18.6 24.6 (5.9)
2007 16.4 19.1 (2.8)
2006 22.5 28.4 (5.9)
2005 15.4 18.0 (2.6)
2004 21.9 27.3 (5.3)
2003 21.0 22.7 (1.7)
Average (3.8)

This brief summary shows that on average the Colts defense has allowed about 3.8 points less than would be expected by their EPA/P since 2003. This year in contrast they are right on their average. If you add in approximately 1-2 points for how EPA/P may be affected by teams playing a lot more recklessly and committing turnovers above it would be reasonable to assume that the Colts offense helped out the Colts defense to the tune of approximately 5-6 points per game. This is certainly in line with my rough calculation in the original article and is very valuable.

Mike B said...

Buzz - I agree. Interesting how the pattern was so consistent from 2003 to 2010.

Jeff Clarke said...

I like what you are trying to do here and you make a couple interesting points. There are a couple questions I had though.

1) The assumption seems to be that because the offense is so bad, they are giving the ball back very quickly. When Peyton was there, they held onto the ball far longer, thus limiting the drives. I can see how this would work for most good offenses that turn bad, but Peyton was known for a quick strike/hurry up offense.
Did you look at what the Colts' avg offense time of poss per drive was vs the league and vs now? I sort of suspect that it wasn't as good at "keeping them off the field" as implied.

2) You give a lot of attention to turnovers going down because the other team is playing conservatively. While that might be true, I think that the vast majority of defensive stats would probably be better against teams that already have the lead. We hear all the time about how certain teams have high yardage totals simply because they piled them up in garbage time when they were far behind. The corollary would have to be that teams get less yardage and points when they are intentionally running out the clock. I feel like the Colts defensive stats might actually be helped by the fact that they are so bad on offense now. Did you look at how they perform in the first three quarters vs previous years and vs the NFL as a whole? I'd be curious to see those numbers.

3) EPA accounts for starting field position. The lack of turnovers is partially the defense's own fault. The fact that the EPA is so bad is a clear indication that this isn't an illusion based on the quarterback. This really is a horrible defense.

Peyton Manning is clearly a very talented player. In my opinion, he's the best quarterback ever. There is little doubt in my mind the Colts wouldn't be 0-8 if he was playing. However, I doubt they'd be a playoff team. This team has a lot of holes and adding one player wouldn't magically change it.

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