The Red Sox acquired Sandy Rosario in mid-October after the Miami Marlins placed the reliever on waivers. Then, in order to clear room on the 40-man roster before the Rule 5 deadline, Boston designated him for assignment, and subsequently traded him to the Athletics for a player to be named later who turned out to be non-roster minor-league pitcher Graham Godfrey.
Got all that? Those are the steps in the path that have led Rosario back to Boston, again, as the Athletics designated him for assignment days after acquiring him from the Red Sox, leaving him exposed on waivers for the third time this off-season. Boston took Rosario back, now that they have room on the 40-man roster, but at this point it's tough to say if he's going to stick.
The Red Sox have used 39 of the 40 spots on the roster, but that's only because the contracts for Mike Napoli, Shane Victorino, and Koji Uehara are not official yet. Boston is going to have to designate someone -- like poor Rosario -- the next time they need a spot, or they are going to have to make a trade with multiple players on the 40-man roster in order to open up space.
As for Rosario himself, he's the same pitcher he was less than two months ago. He's working on a two-seamer, because his mid-90s four-seamer is too straight. If he can get that to be something for him, he has a decent shot at relieving in the majors, but there's a long line of right-handed arms in front of him in the Red Sox bullpen. With a remaining option, though, that's not such a priority in 2013, anyway.