This guy says it well:
The game was really lost in the third quarter. It is not hard to fathom that the defense would wear down in the final quarter, but when it happened, the Patriots should have had a bigger cushion on the scoreboard. The Maroney fumble was the most devastating play in the game for the Patriots, not the fourth down play or any other missed coverage in the fourth quarter. The Patriots did a great job in containing Manning and his offense for three quarters, but had nothing left for the fourth quarter and could not withstand the final assaults in the end.
On two straight possesions, the Pats turned it over in the endzone. Brady’s interception was forgiveable, Maroney’s fumble was not. If either of those had converted into even a field goal the Patriots would have held on to win.
The 4th and 2? I think it was a reasonable gamble. Getting another 40 yards out of a punt means little against the Colts offense. If the Pats get one more first down the game is over. A gamble it was, but I think it was an okay one. Not to mention that Faulk got the first down. But there is no automatic review at that point and there was no way to challenge the call.
Maroney. What happened to that guy? Every time he touched the ball you knew exactly where he was going. He has no sense of misdirection anymore. When he came into the league he would change direction with one smooth step. Now he dances himself to a full halt and accelerates in the other direction. That takes too long in this league. He can’t run people down anymore, he can’t get around them, he can’t get through them. What happened?
Update: More on the 4th and 2 here. I agree.
You’d have to expect the Colts had a better than 30 percent 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 makes punting the better option.