I'm writing this here so it doesn't get lost in the gamethread comments, and to start a proper discussion about McD's calls on 4th down.
I'll start with the 4th and 3 down 20-13 in the 4th quarter (taken in isolation, i.e. ignoring the decision to go for it on 4th and 1 in the 1st half); most people's reaction to this seemed to be it was a horrible call and they should have kicked the field goal. I take the opposite view though, I think going for it is a no-brainer, here's why.
At the time we needed a touchdown and were 12 yards out, 3 yards from converting a first down. If we kick the field goal, hey, we still need a touchdown and if we get the ball back we're likely 70-90 yards away with possibly 4 minutes or less to go. To sum up, we go for it and don't get it, we need a touchdown and the Colts have the ball on their 12, we kick it, we need a touchdown and the Colts have the ball on their 20, essentially no difference. The benefits of going for the TD clearly outweigh the negatives from turning the ball over without any points.
The call in the first half, the 4th and 1, I disagree with. I go for the 3 points there, as I always would in the first half, because you never know how the game is gonna shape up in the 2nd half, and points on the board is preferable to me in that situation (as has been pointed out, that then makes the field goal on 4th and 3 an obvious call, to turn it into a 1 point game). However, I know a ton of coaches in the NFL who go for it on 4th and 1 in that situation, some of whom are going to the hall of fame, so it's hardly a horrendous radical decision.
I'm not a McDaniels apologist, he makes decisions about personnel and play calling that I quite often disagree with, but I think criticising this decision is borne out of frustration rather than an appreciation of the game situation.