Clayton Mortensen was optioned to Pawtucket in order to make room for trade-deadline acquisition Craig Breslow less than a week ago, but he's now back with the Red Sox thanks to a loophole in options. Mortensen is a pitcher, so a pitcher needs to head to the disabled list in order for him to return to the majors before the 10-day waiting period has ended. Vicente Padilla is the injured pitcher in question, making room for Mortensen's return to Boston.
Padilla is dealing with some arm soreness, specifically biceps and triceps, and it looks like he'll get the rest he needs to recover while on the 15-day DL. Like essentially everyone else in the pen, Padilla has been very good in a post-April 21 world, when the entire pen imploded against the Yankees. In the 31 innings and 36 appearances since, Padilla has struck out 34 hitters against nine walks, and posted a 3.41 ERA. Not epic setup work by any means, but still very solid.
Mortensen owns a 1.17 ERA with the Sox, as well as a career-best 2.4 K/BB. He's cut into his homers, walks, and added to his strikeouts in his 23 frames in 2012, and has also performed exceptionally down in Triple-A Pawtucket. (You could see this coming, though not to this extreme degree, as early as Mortensen's first appearances with the Red Sox.) He's not low-one ERA good -- who is, really, besides maybe Atlanta's Craig Kimbrel -- but even his 3.64 FIP shows some quality. As long as he can keep the ball on the ground, in the park, and limit his walks as he's done, then he's useful for the Red Sox, especially since he can give them multiple innings of work.