I just used those two teams as examples. I didn't take the time to fully research the injury history of every team. I did find one source, fangraphs, that shows that for the 2013 season the Sox were in the middle third for days lost due to injury (http://www.fangraphs.com/blogs/2013-disabled-list-team-data/) Sure, in an ideal world DD would have obtained another TOTR SP (at great cost, no doubt). I do not think that was a realistic expectation after obtaining an ace. Henry simply isn't going to pay for that. Hence, we are stuck with a relatively cheap, if fragile, Clay Buchholz.
Edit: one more graph, from 2002-2011 showing the Sox in the middle of the pack in terms of player days lost on the DL:
http://www.fangraphs.com/blogs/10-year-disabled-list-trends/