I mentioned in the last post that running all 4017 4th down plays through the 4th Down Calculator would take a tremendously tedious amount of time. It was also (fairly) noted that some teams evaluations may be padded by easier situations than others from the last post, causing the data to be skewed. We'll address those concerns in this post by introducing a new statistic that we can use to evaluate each and every single 4th down over the course of the season.
The goal here is to come up with a measure of coach aggressiveness on 4th down. To that end, I collected the data for each and every 4th down play over the course of the season (4017 plays in all). Then each one was mark simply as whether the coach went for it or not.
A coach will opt to go for it usually based on 3 variables - the distance to go, the position on the field, and the game situation. For the third, I came up with a measure that I call the Desperation Score. It is simply the score difference divided by the number of minutes remaining in the game. Being down a lot with little time remaining would create a large negative Desperation Score, making it more likely a team would go for it in that situation (in theory).
I used these three variables to run a logistic regression to determine the likelihood a team will go for it in a given situation. For instance, on a 4th and 1 from the 15 yard line in a tie game, a team will go for it roughly 34% of the time. Using this, I determined how more or less often a team went for it on 4th down than an average coach would have given the same situations.
This measure I introduce as the Bravery Against League Level Spunk (B.A.L.L.S.). This statistic is expressed as a percentage, and therefore you can determine how much larger or smaller a coaches B.A.L.L.S. is compared to league average.
Bravery Against League Level Spunk
And now we get the same result that we've seen throughout all of these reports for the San Diego Chargers. Mike McCoy was the least aggressive coach in the NFL last year, by a fairly wide margin. The Chargers went for it on 4th down nearly 7% less than one would expect given the same set of situations.
An even wider margin is between the top two teams in going for it. The Brown, coached by the now-fired Rob Chudzinski, went for it on 4th down nearly 9% more often than league average. In second place, the Jaguars showed that their results from the last post was not simply a result of game situations, they genuinely went for it far more often than most coaches do.
The biggest surprise, in my personal opinion? Jim Harbaugh coming in only 25th in the league when it comes to 4th down aggressiveness. Also, despite reputation, Ron Rivera and Bill Belichick displayed fairly middle-of-the-road values this past season. I discussed the possible reason why for both in the last post, so I won't rehash it here.
At least one team with a reputation for aggressiveness was near the top, with Sean Payton and the New Orleans Saints coming in as the 5th most aggressive team on 4th down last season. Chip Kelly also earned his aggressive reputation, with the Eagles coming in at 6th. Like the last post, I found myself surprised to see the Bengals near the top after the exceptionally timid playoff game against the Chargers.
Keep in mind that this statistic doesn't measure whether it was right or wrong for a team to go for it in any given situation. It is only meant to measure how aggressive a coach was. A coach can be aggressive and go for it on 4th down, but it could be the wrong decision to make. These stats are based on league average, and not on where the league should be.
That being said, it has been shown in numerous studies (including many in academic journals) that coaches are not nearly aggressive enough on 4th down. Being the least daring coach among a group of coaches who aren't nearly bold enough is a mark that Mike McCoy has room to improve.
On a final note, this is all meant to point out a clear area of improvement for Mike McCoy and the San Diego Chargers. There were plenty of things that he did well. His pregame preparation was among the best in the league, as the team often came out well prepared to face an opponent. Outside of John Pagano, he employed a highly effective coaching staff. Fourth down decision making is an area where he could quickly and easily make himself even more effective at getting the absolute most out of his football team.
The same could be said of many NFL coaches. If the NFL wants to improve its product in a very easy manner, providing an course on Game Theory to its coaches would be simple solution. The overall product would improve, and games would be higher scoring and more exciting, with more plays that matter. I'm not entirely sure that is what the NFL wants, though. More punts mean more commercial breaks, after all.