He says he's sore.
http://fullcount.weei.com/sports/boston/baseball/red-sox/2010/05/27/matsuzaka-lower-body-soreness-affected-outing/
This is kind of what Gammons was talking about one day on WEEI in Boston, he said it following Matsuzaka's bad outing vs. the NYY. Daisuke basically said he wasn't totally comfortable with Vmart or the pitches he called. Gammons said it's ironic since there were times that Dice K didn't act comfortable with Varitek.
In other words, it's Dice K that's not comfortable with himself. Gammons said that Red Sox players have said "it's just always something with him, it's never his fault."