From Mike Bauman:

... [Posada] said that on Saturday, after throwing well during the course of the game, he felt some pain on a throw to third base after a strikeout. Arriving at Progressive Field on Sunday, Posada attempted to warm up, but he could not throw without considerable pain.

Earlier tests indicated that there was no structural damage to his right shoulder. But Sunday's experience made Posada wonder about that.

"The MRI showed a strained muscle," Posada said. "I think it's more than that."

Doesn't sound good. Peter Abraham reports that, with Chad Moeller DFA'ed, Chris Stewart is likely to receive a promotion to back up Molina.