Saturday, November 06, 2004

Football Picks – Week 9: Thought I forgot about these, didn’t you? We're going to try something a little different this week.

There is a site you may have heard of called Football Outsiders where, over the past couple of years, they have been working hard at doing deep statistical analysis of football. In the same vein as has been done for many years in baseball, where you may have heard the term Sabrematics to describe it. (Interestingly, the godfather of Sabrematics is a man named Bill James, who for many years produced the annual Baseball Abstract, an exhaustive compendium of baseball statistics. This past year, he was hired by the Boston Red Sox as a consultant. Do the math.)

FO has developed a formula called DVOA, which stands for Defense-adjusted Value Over Average. In their own words:
Every single play run in the NFL gets a "success value" based on this system, and then that number gets compared to the average success values of plays in similar situations for the entire season for all players, adjusted for a number of variables. These include down and distance, field location, time remaining in game, and current scoring lead or deficit. Rushing plays are compared to other rushing plays, passing plays to other passing plays, tight ends get compared to tight ends and wideouts to wideouts.


By adjusting each play based on the defense's average success in stopping that type of play over the course of a season, we get DVOA, or Defense-adjusted Value Over Average. Rushing and passing plays are adjusted based on down and location on the field; receiving plays are also adjusted based on how the defense performs against passes to running backs, tight ends, and wide receivers.

You could read the whole thing, but I'm pretty sure your head would explode. Bottom line is, they come up with a percentage value for each team in the league. A positive percentage means better than average, a negative percentage worse. (They also apply this formula to individual players, but that's not relevant here.)

Now, the folks at FO go to great pains to point out that their numbers are NOT meant to be predictive. They don’t take into account things like injuries and such. But, if one assumes they are on to something, one might look for discrepancies between DVOA and the point-spread, for gambling guidance. Mighn't one?

Here are the spreads (probably gone by the time you read this). Here are the DVOA ratings through week 8. This time I'll do the math.

There are two games where the DVOA difference is over 40%. Seattle (11.0) at San Francisco (-35.3) -- the spread is Seattle -7. New England (31.9) at St Louis (-18.0) -- the spread is New England -1. I'm going to take that favorite in both these, on the principal that such a large difference really tilts the scales in my favor, especially regarding the Patriots, although it's easy to make a case for the Rams given the New England injuries.

Next, Houston (10.0) at Denver (8.4) -- the spread is Denver -6.5. These are the two closest in DVOA and Houston is actually ranked slightly better. Given the big spread for Denver, I'll take the Houston and the points.

The only other game where the favorite in the spread has a lower DVOA than the underdog is Arizona (-9.7) at Miami (-37.6) -- the spread is Miami -3. Notice how I have not said Miami is not as bad as everyone thinks. I'm pretty much cured of that particular delusion. So we'll take the Cardinals and the field goal here.

Provisional comments: These are not picks, just observations. Other games that look out of line are the Jets -3 over Buffalo when their DVOA is 26.1 points greater and KC over the Bucs by 3 when their DVOA is 30.8 greater. You'd think that much of a difference would be worth more than a mere field goal. Then there's the Philly versus Pittsburgh pick 'em, when Philly is 16.8 points greater in DVOA.

To recap, my official picks are:
  • Seattle -7 over San Francisco

  • New England -1 over St. Louis

  • Houston +6.5 over Denver

  • Arizona +3 over Miami

This could be interesting. I may try to keep this going over the next few weeks to see how it averages out.