Adam Steele is back for another guest post, with today’s work being initially published at The GridFe. You can view all of Adam’s posts here. As always, we thank him for contributing.

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I’ll start by stating the obvious: QB wins is a terrible metric for evaluating the performance of quarterbacks. But since this criteria remains at the forefront of the public discourse about NFL signal callers, I figured it would be worthwhile to provide some important context.

The game of football is won and lost in three phases, two of which have very little to do with the QB. In this post I’m going to present a cursory analysis of which quarterbacks benefited the most and least from the play of their teams’ defenses and special teams.

When I reference defensive support, I’m actually referring to the points allowed by a given quarterback’s team compared to the average team during that season. This is not an exhaustive study; my numbers do not adjust for field position, number of drives, turnovers, weather, or any other hidden variable that affects points allowed. But including all the noise also includes all the signal.

From the quarterback’s perspective, it doesn’t matter why his team gave up x number of points – his chances of winning the game are the same (or nearly the same) regardless. If his team allows 35 points, it doesn’t matter to the QB whether his own defense was bad or the opposing offense happened to be a juggernaut. If his team allows only 10 points, it doesn’t matter to the QB whether his defense was stout or the opposing kicker missed three field goals. This is why I’m content to use straight points allowed and ask the reader to make common sense adjustments for QB’s in extreme circumstances.

I collected data from the top 100 quarterbacks in career pass attempts (modern era) plus Hall of Famers and Super Bowl winners outside of the top 100. I only wanted to count games in which the QB played a significant amount, so I set a threshold of 14 pass attempts for a game to count (14 attempts per game is the NFL’s official minimum for rate stat leaderboards). It doesn’t matter whether the QB started the game or not, as such data gets murky the further in time we look back (for another look, here is an old Chase article on points allowed per game in games started by each quarterback). Playoff games are included in the points allowed totals as well as league baselines; said baselines are calculated by removing the points allowed in qualifying games of the QB is question, then finding the league average points per game in all other games during a given season.

In the two tables below, Win % is from qualifying games only, O/U is the number of games over or under .500 in qualifying games, and Playoffs indicates which round of the postseason was reached the by the QB’s team (even if he didn’t play in the postseason).

Here are the top 100 seasons of defensive support among the quarterbacks in my study:

This really hammers home the importance of points prevention in QB wins. A full 92 of 100 reached the postseason, and this includes a number of seasons win which the QB himself played rather poorly. Narrow it down to the top 20 seasons of support, and the QB went on to win the league championship or Super Bowl a remarkable 14 times. Once again, I feel compelled to state the obvious: winning a ring is far more likely when the entire team plays great football around the QB.

Now the bottom 100 seasons of defensive support:

Here we see a bleak portrait of QB’s who were saddled with bad defenses. Only seven of 100 reached the playoffs (and one of those came as a backup), and only one made it to the Super Bowl (with a 9-7 team). Even the best QB seasons are usually torpedoed when paired with a terrible defense.

To show the stark contrast between strong and weak defensive support, this visualization combines the 200 QB seasons from the two tables above. The data points are sorted by defensive support on the x-axis and games over or under .500 on the y-axis. Notice how on the vertical scale, there is little overlap between the clump on the left and the clump on the right. With only a few exceptions, QB’s with great defenses won more games than those with terrible defenses. Shoutout to Kurt Warner for bucking the trend twice!

Helmet knock to Bryan Frye for helping create the visualization and to @ToddyMalone for compiling the data for league baselines.