Thinking about football statistics

While Bill James and his Sabermetrian disciples revolutionized analysis of baseball over the past generation, no similar movement took place in regard to analysis of football. However, as this NY Times article reports, football at the highest levels is increasingly embracing Sabermetric principles:

Now the sabermetric revolution may be gaining a toehold in football as well. And here too the center of the revolution can be found in Massachusetts, where Coach Bill Belichick has led the New England Patriots to victories in two of the last three Super Bowls.
Belichick is known for his unorthodox strategies: being more willing than most to not punt on fourth down; running the ball far more than average in certain crucial situations; and eschewing two-point-conversion attempts in situations when orthodox doctrine recommends them.
Not coincidentally, experts in the world of football statistical analysis endorse all these strategies. For example, David Romer, an economist at the University of California at Berkeley, published a working paper arguing that conventional football wisdom led to far too much punting. Romer analyzed thousands of plays and calculated the chance of scoring from any position on the field. Based on that, he gauged the relative worth of the field position gained by punting against the lost opportunity to score. Romer found that football coaches punt far more than they ought to — perhaps acting out of fear of the worst outcome (going for it on fourth down and failing), rather than rationally balancing risk and reward.
Romer’s paper, “It’s Fourth Down and What Does the Bellman Equation Say? A Dynamic Programming Analysis of Football Strategy,” is far from light reading, so it came as a shock to Romer when he learned that Belichick, who was an economics major at Wesleyan University, had read it.

The main thrust in football statistical analysis is the development of a metric known as “defense-adjusted value over average,” or “DVOA.” The statistic takes into account that not all yards gained in football are created equal. For example, gaining 5 yards on third down and 4 is more beneficial, on average, than gaining eight yards on third and 10. Aaron Schatz over at FootballOutsiders.com is doing the best analysis with DVOA:

Just as it is in baseball sabermetrics, context is crucial to Schatz’s analysis. Schatz rates every play a team runs by comparing it with the league average performance for plays in as close to that situation as possible. In Schatz’s analysis, the relative success of a play is determined by, among other things, the down and distance, the current score, the field position and the opponent’s strength. DVOA, in short, is an attempt to create a tool of analysis for football similar to such Jamesian baseball statistics as offensive winning percentage, runs created and OPS (on-base percentage plus slugging percentage).

Meanwhile, the lack of refined football statistics obscures just how phenomenal a season Peyton Manning this seasons. Although Manning has received a fair amount of publicity over the fact that he will break Dan Marino‘s record of 48 touchdown passes in a season, Allen St. John in this Wall Street Journal ($) piece observes that Mannings’ excellence is better reflected by another key passing statistic — yards per pass:

For pro quarterbacks there’s no statistical Holy Grail. The conventional milestones Mr. Manning is approaching don’t quite resonate. We have developed a benchmark of our own that should make watching the rest of Mr. Manning’s historical season all the more compelling.

10 Yards per Attempt: What’s the essence of football? Almost every time the referee spots the ball on first down, a team has one goal — move the ball 10 yards and earn another set of downs. In a game of variables, it’s the one near-universal. By the Numbers has long touted YPA as the game’s most revealing passing stat because it factors in all the qualities that a great quarterback needs. Accuracy is important, but so is the ability to go deep.
And 10 yards per attempt is near perfection. It means that almost every time a quarterback throws, the linesmen move the chains. And while it’s been achieved in the past by greats like Sid Luckman and Otto Graham, it’s a goal that has become elusive in the modern NFL. Mr. Manning’s YPA of 9.41 is the best single-season mark of any post-merger quarterback with more than 350 attempts in a season. Indeed, just topping nine yards per toss puts Mr. Manning in some pretty heady company. Only four other post-merger QBs have been able to top nine yards per throw for a full season, and three of them made the Super Bowl in the year they did it.

The three Super Bowl QB’s who topped nine yards per pass were Marino, Joe Montana, and Boomer Esaison. Who was the other quarterback who averaged more than nine yards per pass in a season?
Lynn Dickey of the Packers in 1983!

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