Daisuke Matsuzaka, SP
Matsuzaka had his rehab clock reset after he required an injection into his trapezius muscle. He's made two starts since then, and has been effective, albeit brief, in those appearances. Combined, he went for 10-1/3 innings, with six strikeouts and just one walk. Maybe most importantly, he gave up just the one homer -- Dice-K has had some odd trouble with the long ball during his rehab assignment.
He hasn't been throwing significant innings as he works his way back, but according to Matt Huegel, Dice-K felt "strong" after being lifted in Thursday night's game, as if he "still had a lot left in [him]." That's a good sign for Matsuzaka, who has never exactly been an innings eater in his career, whether from inefficiency, fatigue, or injuries. (Or, on those nights, where it's a little of all three at once.)
Dice-K isn't some cure-all for the Red Sox rotation, but once he's ready to come back, he's part of their starting pitching depth. And, should someone go down with an injury, or one of Clay Buchholz or Daniel Bard fails to be consistent, he could spell them as they work on their issues, or simply give Bard a breather the schedule might otherwise not allow.
Clayton Mortensen, RP
Mortensen never did go back to starting when he was optioned back to Pawtucket. He's been a bit more susceptible to walks since going back to Triple-A, but not at an alarming rate, as he's struck out nine and walked five in those 9-1/3 frames.
He's an intriguing arm for the Red Sox system, but given the way things have worked out for the bullpen as of late, there's no need to necessarily rush him back to the majors, either. Mortensen (and Junichi Tazawa) both have plenty of team control left, meaning that, if they can't be important parts of the 2012 pen, they will still be around in 2013 if necessary. And, as Matt Albers reminded us last year, first-half success for a reliever doesn't necessarily mean that you can depend on them all year. Mortensen might end up with another shot, and he's earned it, even if you'd like to see him keep that walk rate down given his past.
Alex Wilson, RP
Speaking of relievers with plenty of team control left, Alex Wilson's bullpen experiment has come along nicely. In his last 10 appearances, the right-hander has thrown 17 innings, striking out 20 (10.6 per nine) while walking seven. Those 3.7 walks per nine might seem like too many, but for a reliever whiffing batters at that pace, you can forgive a whole lot.
It also helps that Wilson has given up just five runs in that stretch, and nary a homer. He's still been an extreme fly ball pitcher since moving to the pen, and that's something he'll likely have to work on before coming to the bigs for good, but this is still progress for an arm most people weren't paying much attention to prior to 2011.