While the pitching might be "thin" Farrell's background is that of a pitching coach, and a good one at that. Helping develop Lester and Buchholz in Boston. I wouldn't be so quick to give up on Drabek yet.
But the Red Sox have Bucholz returning too. Really there rotation is pretty much set for the top 3. Dice K is decent enough for a fill in #5 starter when Beckett makes his annual stint on the DL.
I would like to see the Sox sign Oswalt as a #4.