Monday, November 16, 2009
Belichick Was Correct
Feeling a touch under the weather I didn't see the end of the fantastic Colts vs. Patriots. Of course it was hard it ignore the media outlash against Belichick this morning. After hearing the description of said 4-2 call my first though was, "Wow, seems like an EV calculation." And my second thought was, "There's no way your typical ex-football player / writer understands that concept." And sure enough, ESPN and the general media are filled with this incorrect nonsense that Belichick made a horrible call. The simplicity of their analysis distilled down to "You have to trust you defense, man."
How about a little math? Any good poker player shoving ATC from the cutoff understands they have both fold equity and some chance of winning if they do get looked up. So if they make the first down they win 100% of the time (i.e. everyone folds to your shove). And if they fail to get the first down they still have a chance of their defense stopping Manning and company, however small that chance is (much like your rags beating QQ). So add those two together and compare against the result of a typical punt with 2 minutes left.
Well, Advanced NFL Stats did the math. Guess what? Belichick was right.
New England coach Bill Belichick is taking a lot of heat for his decision to attempt a 4th down conversion late in the game against the Colts. Indianapolis came back to win in dramatic fashion. Was the decision a good one?
With 2:00 left and the Colts with only one timeout, a successful conversion wins the game for all practical purposes. A 4th and 2 conversion would be successful 60% of the time. Historically, in a situation with 2:00 left and needing a TD to either win or tie, teams get the TD 53% of the time from that field position. The total WP for the 4th down conversion attempt would therefore be:
(0.60 * 1) + (0.40 * (1-0.53)) = 0.79 WP
A punt from the 28 typically nets 38 yards, starting the Colts at their own 34. Teams historically get the TD 30% of the time in that situation. So the punt gives the Pats about a 0.70 WP.
Statistically, the better decision would be to go for it, and by a good amount. However, these numbers are baselines for the league as a whole. You'd have to expect the Colts had a better than a 30% chance of scoring from their 34, and an accordingly higher chance to score from the Pats' 28. But any adjustment in their likelihood of scoring from either field position increases the advantage of going for it. You can play with the numbers any way you like, but it's pretty hard to come up with a realistic combination of numbers that make punting the better option. At best, you could make it a wash.
It's freaking Moneyball all over again, except we don't have Joe Morgan around to sound like a fool.
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