On Thursday, Phillies starter Roy Oswalt was removed from a game in which he was ineffective, and in which he was ineffective because of back discomfort. He was scheduled for an MRI on the following Monday, and admitted that he'd been pitching through back pain for several weeks.
Initially, the Phillies said that Oswalt would miss at least his next scheduled start. On Friday, though, they've taken the next step and placed Oswalt on the disabled list.
The DL stint means that Oswalt will miss at least two starts, rather than one, and gives the Phillies a little more roster flexibility as they await word on the severity of his injury. Oswalt going on the DL was probably inevitable anyway, given that back problems don't just disappear or heal overnight.
Scott Mathieson was recalled to take Oswalt's place on the roster, but his rotation spot will be occupied by Kyle Kendrick for the time being. With Roy Halladay, Cliff Lee and Cole Hamels, the Phillies aren't exactly starved for quality pitching, but they are now working without both Oswalt and Joe Blanton, which wasn't part of the original plan.