Red Sox's Sean O'Sullivan: Lands on 15-day DL

O'Sullivan was placed on the 15-day DL on Saturday with left knee tendinitis, Tim Britton of the Providence Journal reports.

This move conveniently opens up a roster spot for Brad Ziegler, who is expected to be activated Sunday. O'Sullivan has struggled in 21.1 innings with the big club this year, but the Red Sox have won in all four of his starts with the offense exploding for 39 runs in those four games. It's entirely possible O'Sullivan will return to a starting role once healthy, but his window to start may shut in a hurry as the Red Sox figure to be in pursuit of rotation help at the trade deadline.