What was lost? A causal estimate of fourth down behavior in the National Football League

Abstract

In part driven by academic research, perception in the sports analytics community asserts that coaches in the National Football League are too conservative on fourth down. Using 13 years of data, we confirm this premise and quantify the unobserved benefit that teams have missed out on by not utilizing a better fourth down strategy. Formally, teams that went for it are paired to those who did not go for it via a nearest neighbor matching algorithm. Within the matched cohort, we estimate the additional number of wins that each NFL team would have added by implementing a basic but more aggressive fourth down strategy. We find that, on average, a better strategy would have been worth roughly an extra 0.4 wins per year for each team. Our results better inform decision-making in a high-stakes environment where standard statistical tools, while informative, have possibly been confounded by extraneous factors. "There's so much more involved with the game than just sitting there, looking at the numbers and saying, 'OK, these are my percentages, then I'm going to do it this way,' because that one time it doesn't work could cost your team a football game, and that's the thing a head coach has to live with, not the professor."-Bill Cowher, former head coach of the Pittsburgh Steelers (Garber, 2002)