I think there may be a defensible argument to be made, especially in a short-series situation, for using Molina in place of Posada to catch Burnett.

Sure, overall Posada in the lineup is worth some tenths of a run a game on average more than Molina. But if you think that there is a decent possibility that Molina behind the plate rather than Posada when Burnett pitches is the difference between a Burnett meltdown and not (which is the difference between, say, a Burnett 1 or 2 run start and a 7 run start), then the argument comes clearly into focus. You are giving up a significant offensive advantage to try to minimize the possibility of incurring a much larger, totally game-changing disadvantage. And when you are looking at a 5-game series rather than the long haul, minimizing the possibility of a worst-case outcome becomes much more sensible.

Now I have no idea what the probability is that Molina could keep Burnett from a meltdown that Posada wouldn't. Yankee management knows the inside scoop on this much better than any of us. So if they are making this type of decision, I'm sure they think there is a justifiable reason for it, even though it doesn't appear clear on the outside.

Remember, if it is the offense we are talking about in supporting Posada over Molina, Posada could always DH. Then we could discuss the downgrade from Matsui versus the defensive upgrade, and Matsui could be the one whining about how the Yankees had better win the game he is out (as if his presence in the game guarantees victory).