Sunday, February 02, 2014

Accurate Performance Metrics For NFL Teams

Super Bowl Sunday brings visions of Americans gorging themselves on fast foods high in corn syrup and saturated fats.  Most Americans devolve to tribal loyalties today and cheer on their favorite gladiators while I engage in dispassionate analysis.  Professional football needs some serious Moneyball disruption.

Las Vegas oddsmakers and professional NFL team scouts have been using the wrong metrics to evaluate gridiron performance.  The most commonly cited metrics include yards per game (YPG) and team yards per play.  The NFL's official team stats page has tracked both of these for each team since 1970, with some select stats predating those years.  Both of those metrics have little correlation with either season win percentage or Super Bowl championship.  I ran the numbers myself on those stats until I realized I was wasting my time.

Results-oriented metrics matter.  The winning result in football is scoring points, not accumulating yardage.  Football coach Tim Chou proposed the "yards per point differential" at an MIT Sloan Sports Analytics Conference.  Critics have questioned its relationship with skill while favoring yards per play.  There's an intuitive link between yards per play and the on-base percentage of Moneyball fame, but there's one crucial distinction.  Hitting is a one-on-one competition between a batter and pitcher.  Scoring is a total team effort, reflecting the coach's ability to call plays.  I think yards per play still bears too much similarity to older metrics like YPG.  Scoring relationships like yards per point can be linked to individual players, which in turn influences their monetary value when under contract.

The point of finding better metrics is to optimally allocate the limited resources of NFL coaches and managers.  Coaches wasting time on plays and drills that gain yards will not raise their winning percentages if they don't score points.  Managers overpaying for players will ignore the unheralded value of players whose ability to score is hidden in overlooked stats.  NFL teams need some Moneyball disruption.