SPRING 2024

AUTHORS

Matthew Ladden, Trinity School
Ethan Seung, Harvard-Westlake School

ABSTRACT

This paper evaluates the per-play impact of special teams on the winning percentage of NFL teams compared to offense and defense. Employing data from the 1999-2022 NFL seasons in the nflfastR database, we developed a new calculation for Expected Points Added (EPA) to accurately assess the contribution of special teams plays, including punts, kickoffs, and field goals, independent of coaching decisions. This methodology allowed us to create our Special Teams Performance Index (STPI), a composite metric that consolidates the performance of all special teams units on a team. We then used STPI in combination with offensive and defensive ratings from ProFootballReference in a regression model to evaluate the importance of special teams on winning percentage. Finally, since there are fewer plays on special teams than on offense or defense in a game, we adjusted the resulting numbers to find the impact on a per-play basis.

We found that an individual play on offense is 3.6 times and that an individual play on defense is 2.6 times more impactful on winning percentage than a play on special teams. Our results can be extrapolated to coaching decisions concerning playing starters on special teams. A special teams play has a significantly lower impact on a game as compared to one on offense or defense, and plays on special teams have a significantly higher per-play injury rate; therefore, starters on offense and defense should generally not be used on special teams.