Tuesday, January 13, 2009

The importance of Run Defense

I just read an excellent post about the importance of Run Defense over at the blog "Advanced NFL Stats" located at http://www.advancednflstats.com/2009/01/year-of-run-defense.html  .   Its also one of the blogs that I follow.

The gist of the blog is that the team with better run defense wins 67% of games in the playoffs yet only 48% of the time in the regular season.  

I hope that those win percentages were calculated after the season with "end of season" ranks rather than updated after each game throughout the season.  

Here is a comment I made after reading their article:

Part of the problem when analyzing statistics over a long period is changes in the way statistics are measured. 

This doesn't have as big of an effect in football but in basketball, who gets credited with assists, steals, and some rebounds are depending on the scoring table and changes in how they are perceived. 

The other major thing I'd point out is the *absolute* strength of a team's run defense. Some years the best run defense in the league might be (if it were transported through time) only the fifth or sixth best in the league now (or vice versa). So maybe what matters is that your run defense is "good enough" rather than simply "top ten". The first term is an measure of absolute skill, the second a relative term.

The concept of being "good enough" rather than using relative rank is something I got from reading Malcolm Gladwell's book "Outliers" where he discusses that once you are "smart enough" you can succeed to the highest levels in out society and excess intelligence is not a predictor of how well you do; one simply has to be "smart enough".  

Also, consider that players playing the playoffs are trying harder than the regular season. Think about it, intensity and physicality go up in the playoffs, the refs are less inclined to alter a game with borderline penalties, players are typically more experienced, more veteran, better able to get away with physical play. 

Coaches don't want to "get fancy" and risk losing their job because of poor play calling. Remember: conservatism is rewarded in the NFL by owners and fans alike. Its much easier to blame the offensive line if you get stuffed on 4th and 2 than to blame them if you try a halfback pass on 4th and 2 and the fan base calls for you to be fired because of a single bad outcome in a special play.

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