What Makes Teams Win? 4

This is the 4th and final part of an article discussing the relative importance of factors in winning NFL games. Part 1 is here, part 2 is here, and part 3 is here.

ANALYSIS

A good passing game is far more important than a good running game in the NFL. It’s at least twice as important, and probably even more so. If we include interceptions as part of the passing game, passing efficiency and interception rates dwarf the importance of running efficiency by a factor of 4 to 1.

An alternate way of looking at interceptions is that they are a threat to the passing game, so their importance should be subtracted, not added, to passing efficiency to properly compare running and passing. Although it's a valid consideration, you cannot win without passing, and so the risk of interception is not optional. The bottom line is that if a team would rather be good at passing or good at running, it should choose passing.

Part of the conventional wisdom about the running game in the NFL is that it “sets up” the passing game. It keeps the defense off balance and unable to focus exclusively on defending against the pass. This may be true up to a point, but it appears that the balance between defending against the run and the pass is far out of equilibrium.

If a good running game gives a team an advantage in passing then we would see a positive and significant correlation between offensive running and passing efficiency. In fact, the correlation is 0.13, which is very weak and not statistically significant. Running well does not prevent interceptions either. The correlation between running efficiency and interception rates is 0.12. Further, including an interaction variable (running * passing) in the regression model results in an insignificant coefficient and a marginally weaker model. We have to conclude that running and passing are fundamentally independent of one another.

It appears that offensive passing is more important than defensive passing, and that offensive running is more important than defensive running. We might conclude that offense is more important than defense, but it may not be that simple. For starters, that violates the symmetry of the sport. Points allowed are equally as important as points scored.

One explanation becomes clear when you add the coefficients of offensive passing and offensive interceptions (1.14 + 0.45 = 1.59). Compare that with the sum of defensive passing and defensive interceptions (0.92 + 0.76 = 1.68). We see that the balance between offensive passing and defensive passing starts to equalize.

Comparing the sum of all offensive weights with the sum of all defensive weights yields a very balanced result. Offensive variables add up to a total weight of 2.38 vs. a total weight of defensive variables of 2.34. Although the defensive variables appear slightly stronger, the relative sums of the weights are within 1.7%--remarkably balanced.

Passing is indeed far more important than running, and although offense appears more important than defense, they're equally important.