Scheduled to start on September 9th, Daisuke Matsuzaka is currently spending his Sunday afternoon getting rocked in the first inning of a AA rehab start against the New Hampshire Fishercats--one of the league's worst offensive teams.
Matsuzaka has allowed 5 runs on 3 walks and 4 hits including a home run in the first inning, and doesn't seem to be headed for two. It's worth noting that this is Daisuke's first start in months, but if he doesn't show marked improvement in his next rehab start, it seems doubtful the Sox would take a chance on letting Matsuzaka start again down the stretch before he's shown success.
UPDATE: Matsuzaka did come out for the second recording a short perfect inning including a pop up and strikeout. He appears to be done.
If Dice-K cannot return, the Sox would yet again be struggling to put together a rotation. Beckett, Lester, and Buchholz now seem locked into their roles. Paul Byrd pitched well today and will hopefully continue to be the reliable 5th starter he was last year for the Sox, but Tim Wakefield's health is questionable, which could leave an open spot.
The Sox would have relatively limited choices. The 2 obvious names are Junichi Tazawa and Michael Bowden, but both were shelled in their short MLB stints (as good as Tazawa's results were in a few games, he was hit hard). Another possible option would be Randor Bierd, who was recently converted from a reliever into a starter. He's had some limited and unimpressive major league experience in Baltimore out of the pen, and has been similarly mediocre in the minors, but it might be worth it to take a shot on a new face, and in the process avoid ruining Tazawa and Bowden.