In return they get Jason Bulger, a hard throwing relief pitcher a few years removed from Tommy John surgery.
I suppose I ought to write something about this. I've already posted my thoughts on the Rev's site, but my first thoughts on this are that it sounds like a decent deal with good potential, and even if it fails, I don't think it will hurt the Angels too much. Almost no one projects Callaspo as more than a good Major Leaguer at best. We're not talking about a future hall of famer, though I wish him well. On the other hand, the Angels brain trust has a good track record with hard throwers that no one else seems to want too much (see Donnelly and Weber). He gives them some depth in the bullpen.
What's better is what this trade reveals, which is the rising star of Howie Kendrick. This deal was necessitated by Kendrick's terrific play. It looks like he'll be starting the season in AAA. Callaspo, while a good prospect, hadn't shown any power, and he was the fourth best middle infield prospect on a team full of them. He was expendable. And if he pans out, he'll be the double play partner of the second best shortstop prospect in baseball, Stephen Drew. Good luck to him.