The NFL season started Sunday—sorry, we don't count Thursday football as the real season-opener—so it's time to get used to sports fanatics babbling about defense winning championships.
There's only one problem with that refrain: It's not entirely true. While there haven't been many Super Bowl winners that were defensive slouches, a recent study that analyzed the past three NFL seasons shows a team's offensive ability is 61% more crucial to winning games than its defensive prowess.
The Weight of a Win
Here's a look at how much, in terms of percentage points, each part of an NFL game makes up a team's victory.
Special Teams 15.7%
Source: Northern California Symposium on Statistics and Operations Research in Sports
The study—written by statistician Keith Goldner and scheduled for presentation next month at a sports-statistics symposium—tracked every NFL game since 2007 to find which part of a team's performance is most highly correlated to winning. Mr. Goldner tracked every drive during those seasons and assigned each one an expected-points value; this number shows how many points a team was supposed to gain over its opponent on offense, defense and special teams. Mr. Goldner then compared this expected team performance to the way the teams actually played, and he used these relationships to show how much each part of the game helps a team win.
The study says offense makes up 52% of a team's victories while defense is worth 32%—this discrepancy is due partially to the leaguewide increase in passing-game accuracy.
Special-teams play is only worth 16% of a team's victories, though that number is actually quite high given that special-teams players aren't on the field for very long. Maybe those punters are more important than we thought.