Running the Numbers: How Much Do Penalties Hurt NFL Teams?
I’ve been fascinated by the relationship between penalties and winning for a few years now, even though I haven’t necessarily written extensively on the subject in this forum. When the Cowboys signed offensive tackle Alex Barron a few years ago, I wrote an article on the negative impact of Barron’s false starts. The tackle had committed 43 false starts over the previous five seasons in St. Louis.
From that post:
Barron’s false starts were responsible for the loss of 24.4 expected points over the course of five seasons, or about five points per year. In essence, each false start cost the Rams 1/2 expected point, which is in line with league averages.
Expected points are one thing, but how do the false starts and subsequent loss of expected points affect a team’s win total? Well, five points over the course of a season translates to just about .12 wins. Thus, Barron’s (and those of Adams) false starts were annoying, but not as costly to a team’s success as you might believe.
One of the things I may have overlooked in that article on Barron is what sort of style of play accompanies certain types of penalties. False starts and other mental mistakes, although often not devastating to a team in terms of lost yards, come with no benefits. Players who frequently false start likely don’t have a tremendous mental grasp in other aspects of their game, such as blocking assignments and so on.
On the other hand, penalties such as roughing the passer and defensive pass interference are the result of aggressive play. The mindset that accompanies such penalties can lead to benefits for a team, such as interceptions and sacks. Thus, although more detrimental than mental errors in a limited sense, aggressive penalties might be the inevitable result of an attacking style of play.
That’s exactly what I found in my latest Running the Numbers post at DallasCowboys.com. Check it out:
On paper, everything adds up for defensive pass interference to lead to defeat. The call itself can be incredibly disadvantageous to a defense, providing the offense with the ball at the spot of the foul, plus an automatic first down. On top of that, you’d expect poor defenses to commit more pass interference infractions because they get out of position. Lastly, bad teams tend to have their defense on the field a lot, i.e. more time to accrue penalties.
However, teams that generate a lot of pass interference calls aren’t actually more likely to lose than those that limit the penalty. Since 2006, teams that have finished in the top 10 in defensive pass interference (meaning they were flagged the least often) have won 7.9 games per season. Those in the bottom 10 have won 8.0 games per year.
You can see above that in four of the past six seasons teams that finished with the most pass interference calls won the same amount or more games than the teams with the fewest pass interference penalties.
As I tracked different types of penalties, I noticed the same trend; those that come as a result of aggressive play (such as pass interference, roughing the passer and illegal contact) aren’t correlated to losing football games. This is so astounding because these penalties are often the most harmful to a team.
I realize looking at defensive pass interference alone results in a limited sample size, but the trend extends over most “aggressive” penalties. I find this fascinating.
The results of this study suggest teams shouldn’t really do everything possible to limit penalties. Aggressive play without penalties is of course ideal, but probably not possible. Some penalties are the result of a specific style of play that, as the numbers show, leads to more benefits than disadvantages. It’s a medium risk/high reward style of play that is superior to the low risk/low reward style of play that characterized the pre-Rob Ryan Dallas Cowboys defense.
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