Over at Baseball Prospectus, Jay Jaffe throws in a highly relevant fact:
It's worth wondering if his problems are of a piece with the concussion scare that sidelined Posada last September and led to his mothballing as a catcher. Since last September 8, he's hitting .160/.280/.314 in 182 plate appearances, about a third of a season's worth.
Here's another fact: Prior to last September 8, Posada's line in 2010 was .262/.367/.485 in roughly 400 plate appearances, or about two-thirds of a season's worth.
Posada's performance is at the heart of this thing. If he's hitting, he doesn't bat ninth. If he's hitting, he's not so terribly frustrated. If he's hitting, Brian Cashman doesn't throw him under the bus. And when a guy goes from Posada's pre-9/8 to his post 9/8 on a dime, you have to really wonder if it's more than about just getting a tiny bit older.
There's obviously some bad luck involved, too; Posada's batting just .164 on balls in play this season, which is just insanely low. Still, I wonder if there's something going on that nobody's managed to figure out yet. And don't be surprised if Posada winds up on the Disabled List before Memorial Day.