Originally posted on 11/16/2009:

It's a really simple math problem on whether or not to go for it in that situation. All you need is to assign probabilities to the following:

Chance of getting a first down on 4th and 2
Chance of Colts scoring a TD from 30 yards out with 1 TO left.
Chance of Colts scoring a TD from ~70 yards out with 1 TO left.
Chance of Pats coming back and scoring when the Colts score (should be slightly higher when not punting because the Colts will tend to score faster)

Hint: even with estimates ridiculously biased towards punting, going for it is still the correct answer by a country mile.

This also ignores blocked punts and long punt returns.