His bat is tremendous, wasn't getting much time lately at catcher because Austin Romine was getting the time there and he's a legitimate MLB prospect. Montero has only really mashed at DH, not the same success at C so far this season. His defense is basically horrendous and he needs all the full time play he can get so his ETA doesn't get delayed another year because 1B is blocked, he's too slow for the outfield, and you don't want to push a kid into the DH role so soon unless there's no other choice.
Yeah, that wouldn't surprise me either. The 2012 ETAs on many of the preseason sites were clearly over the top, I was thinking late 2010. The only way he would stay down until 2012 is if the Yankees refused to see him as anything but a catcher.