Napoli can no longer catch... he's had some serious hip injuries. I don't know the details of his injuries, but he can no longer do the catcher's squat for any length of time.
"...So, Napoli finds himself in a nice position. He also hasn’t sworn off catching again. Napoli has said he has never experienced any symptoms of the avascular necrosis in his hips, but talk of that could still be problematic in free agency."