It's a shame bullpens don't actually win divisions, because if that were the case the Sox would be about seven games ahead of the rest of the AL Central.
With Matt Thornton preparing to close, the Sox bullpen was set up to shut down lefties in any high-leverage, late-inning situation with Will Ohman and Chris Sale poised to be LOOGYs to get, say, Joe Mauer and Justin Morneau out in big spots.
Of course, things didn't work out that way. And that's not in reference to Mauer and Morneau playing minor roles for the Twins this season.
At the end of April, Thornton had an 8.64 ERA with four blown saves. He was unofficially defenestrated from the closer role and, magically, returned to dominant form (regressions can be good things!).
But when Thornton moved back into a setup role, it left the Sox with a glut of lefties for the sixth-eighth innings. And none of them were doing particularly well by early May.
On May 2, Thornton, Sale and Ohman all had ERAs north of 7.00, with Thornton and Ohman sporting marks above eight. Many wondered why Ohman was on the roster in the first place and whether it was time to ship Sale off to Triple-A for some refinement.
Fast-forward three months, and that trio of relievers has been as good as they were bad back in May. Thornton's ERA is down to 3.25; his FIP sits at 2.97. Sure, his strikeouts are down and his walks are up from his 2008-2010 seasons, but he's nonetheless reclaimed his place as one of the more dominant left-handed relievers in baseball.
Sale's been the best of the three, though, bringing his ERA to a cool 2.88 with a 3.22 FIP. Since the start of June, Sale's been nearly untouchable, posting a 1.12 ERA with 29 strikeouts, eight walks and one home run allowed.
And then there's Ohman, who quietly has put together a fine season. His disastrous appearances to start the season April 1 and 3 against Cleveland (2 IP, 6 R) have skewed his ERA higher than Thornton and Sale, but his ERA since those pair of debacles is 2.27 with 35 strikeouts, 11 walks and two home runs allowed.
Sure, Ohman hasn't seen many high-leverage situations. But even as a mop-up guy, he's done an admirable job. And he's done it facing more right-handed hitters than lefties, although he's remained true to form in struggling against righties while succeeding against lefties.
It's not too likely Ohman will earn his $2 million salary for this season based on his current WAR (0.1, worth $0.6 million, according to FanGraphs). Maybe the Sox could've saved $1.5 million going to a young pitcher to fill Ohman's role -- if only they had a major-league ready reliever to come out of spring training with. Tony Pena was supposed to be the team's mop-up man/long reliever, but his injury problems have thrust Ohman into that role.
[Speaking of which, if you feel like arguing against Ohman's salary, you're missing the point. The Sox could've saved about $1.1 million by non-tendering Pena and keeping, say, Jeff Marquez or Lucas Harrell on the roster to fill his role.]
And yes, Ohman hasn't filled the role the Sox envisioned. Paying $2 million to a mopup man is too much, but that's not the point. The point is that, in case the Sox do need that third lefty, Ohman is there and he's a much better bet to get a key out than a guy making the league minimum.
I hardly consider him superfluous to the roster. I'm also not ready to call his addition a good signing, but it certainly hasn't been bad, either.