Hanrahan, 31, has been a rare good thing on a consistently bad pirates team over the past few years. With a 2.59 ERA in some 230 innings, when the Pirates have been able to get a lead to the late innings, Hanrahan has been a reliable workhorse of a closer.
That being said, I'm not sure he makes much sense in Boston.
At 31, Hanrahan is on the verge of free agency, which explains why the Pirates are interested in dealing him. Of course, that also means he's entering his most expensive year under team control, and after making $4 million in 2012 could well bring in $6 million or more in arbitration.
The Red Sox can still afford that without going over the tax, but is a closer the best place to drop their money? Even if Andrew Bailey and Mark Melancon don't bounce back, the Sox have some decent talent in their bullpen and some interesting depth to go with it. Given that their 40 man is full to the brim, the Sox would likely be losing one of the players in the back end of the pen who, if not Hanrahan, could be around for years to come on the cheap.
Of course, it's possible that they'll be losing that player and little else to the Pirates since these contract considerations don't tend to make for the most valuable of trade chips. If you think that would make the deal worthwhile, though, you should give it some more thought after looking at Hanrahan's numbers. Because even if that ERA was plenty low in 2012, the sudden spike to a 5.43 BB/9 and miniscule .225 BABIP make it entirely suspect.
No, it might be best just to move on past ol' Joel Hanrahan.