With the post-season underway, I thought I'd have a little fun running correlations between stats and wins for the 2009 NFL regular season. There are plenty of professionals at NBC, FOX, CBS, and ESPN (just to name the major broadcasters) who slice and dice this stuff for a living, and I'm not interested in trying to give them a run for their money by controlling for other variables, matching up output with active players for various games, and the like. Just the raw correlations for entire teams here:
* not statistically significant at 90% confidence
Points scored is the best predictor of a team's win-loss record. That's hardly surprising, since it's almost like saying a team's number of wins is the best indication of its success. But when considered along with other statistics, it does indicate how good offense (and passing, specifically) has come to supercede in importance good defense in posting a winning record. Every year, though, Chris Collinsworth or Boomer Esiason will remark in the course of a playoff game how crucial a good defense is to move forward in post season, insinuating that it matters more then than it does during the regular season. The NFL's official site archives stats going all the way back to 1932 (in a limited capacity), offering a way to empirically test that assertion for someone interested enough in it to make the required time investment.
The passer rating system as a measurement of QB performance has its critics. It doesn't account for yards gained on the ground or its corollaries, scrambling ability and sacks taken. But it's almost as useful as points scored in predicting a team's record.
Most teams win with their passing games. Of the top ten rushing teams, only four are in the playoffs. And the two odds-on favorites to win the Super Bowl, San Diego and Indianapolis, are #31 and #32, respectively. In contrast, eight of the top ten offenses in terms of total passing yards made the post-season, and only one playoff team, the improbable Jets, can't move the ball through the air.
Although special teams are often accorded one-third of a team's total equation by media figures and putative insiders, the layman's tendency to deemphasize them in favor of offense and defense looks pretty reasonable. It is nearly impossible to predict a team's level of success by looking only at its special teams statistics.
A defense that is worn down by being run at throughout the course of the game fares worse than one that gives up a lot of total yards in the air, statistically speaking. But this is surely obscured by the fact that teams that are winning run while those playing from behind pass.
Turnovers are huge. Penalties are not. Fourth down attempts are too infrequent to be of great consequence in aggregate, but the ability to convert on third down is important. Again, though, better teams are going to have more third and short situations than the Rams or Lions are.
| Offense | |
| Points scored | .88 |
| Team passer rating | .81 |
| Total yards gained per play | .81 |
| Yards gained per pass play | .80 |
| Total yards gained | .77 |
| 1st downs | .70 |
| Turnover ratio | .69 |
| Pass yards gained | .68 |
| 3rd down conversion % | .64 |
| QB hits allowed | (.53) |
| Sacks allowed | (.53) |
| Time of possession | .46 |
| 4th down conversion % | .25* |
| Pass attempts | .14* |
| Run attempts | .12* |
| Yards gained per rush play | .09* |
| Offensive penalty yards | .04* |
| Run yards gained | .04* |
| Pass/run ratio | .02* |
| Defense | |
| Points allowed | (.68) |
| Run yards allowed | (.58) |
| Passing yards allowed per pass play | (.57) |
| Total yards allowed | (.56) |
| Total yards allowed per play | (.54) |
| Opponent's passer rating | (.47) |
| 1st downs allowed | (.45) |
| Sacks made | .41 |
| Run yards allowed per play | (.33) |
| 4th down conversions allowed | (.30) |
| Passing yards allowed | (.24) |
| 3rd down conversion % allowed | (.23)* |
| Defensive penalty yards | .14* |
| Special Teams | |
| Average kickoff (kicking team) | .32 |
| Average net punt yards (kicking team) | .27* |
| Average kickoff return yards allowed | .15* |
| Total penalty yards committed | .11* |
| Average kickoff return yards gained | .05* |
| Field goal % | .03* |
* not statistically significant at 90% confidence
Points scored is the best predictor of a team's win-loss record. That's hardly surprising, since it's almost like saying a team's number of wins is the best indication of its success. But when considered along with other statistics, it does indicate how good offense (and passing, specifically) has come to supercede in importance good defense in posting a winning record. Every year, though, Chris Collinsworth or Boomer Esiason will remark in the course of a playoff game how crucial a good defense is to move forward in post season, insinuating that it matters more then than it does during the regular season. The NFL's official site archives stats going all the way back to 1932 (in a limited capacity), offering a way to empirically test that assertion for someone interested enough in it to make the required time investment.
The passer rating system as a measurement of QB performance has its critics. It doesn't account for yards gained on the ground or its corollaries, scrambling ability and sacks taken. But it's almost as useful as points scored in predicting a team's record.
Most teams win with their passing games. Of the top ten rushing teams, only four are in the playoffs. And the two odds-on favorites to win the Super Bowl, San Diego and Indianapolis, are #31 and #32, respectively. In contrast, eight of the top ten offenses in terms of total passing yards made the post-season, and only one playoff team, the improbable Jets, can't move the ball through the air.
Although special teams are often accorded one-third of a team's total equation by media figures and putative insiders, the layman's tendency to deemphasize them in favor of offense and defense looks pretty reasonable. It is nearly impossible to predict a team's level of success by looking only at its special teams statistics.
A defense that is worn down by being run at throughout the course of the game fares worse than one that gives up a lot of total yards in the air, statistically speaking. But this is surely obscured by the fact that teams that are winning run while those playing from behind pass.
Turnovers are huge. Penalties are not. Fourth down attempts are too infrequent to be of great consequence in aggregate, but the ability to convert on third down is important. Again, though, better teams are going to have more third and short situations than the Rams or Lions are.
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