I see him almost daily and don't think there's anything physically wrong. He is really struggling against lefties (.209) , .256 against righties. I've seen him hit from the left side against some southpaws this season so maybe he is just more comfortable hitting from that side of the plate these days.
The worrisome part to me isn't his avg against righties, which is .265 over the past 3 seasons, but the .209 is way off his .326 avg against lefties the past 3. Plus he tends to fade a bit post break.
I love the guy and he has a ton of value to the Sox for his ability to handle the staff, especially with Papelbon, Lester, and Hansen now in the mix. As for his fantasy value though, it's in a pretty sharp decline.