In 2006, Andrew Miller was drafted. In 2007, he was traded. In 2010, he was given up on. In 2012, he finally found his place.
When it comes to players who were once regarded as highly as Miller was, it's not at all unusual for it to take a while to make the switch from failed starter to decent reliever. No matter where you go, so long as the results weren't too dramatically terrible in the rotation (and, no, a 5.50 ERA does not amount to that), someone will always be wondering "can he start?" Add in the dreams of finding the old potential and emerging as the ace that was promised, and it's a pretty tempting path to steer someone away from.
Still, the Red Sox finally pulled that trigger, moving Miller to the pen as a mostly-but-not-entirely LOOGY, and the results suggest there's actually a place for him in that niche-but-useful role. On the whole, a 3.35 ERA is nothing to scoff at, and a 51:20 K:BB is actually quite good. Miller may have only pitched 40 innings, but with a career-low 3.17 FIP, he was actually worth three times as much as he was last year in 65 frames.
But it's when you break the season down into its components that things really get impressive. Because while Miller showed his same old struggles facing righties, he was completely lockdown while facing lefties. 33 strikeouts in 102 plate appearances, just 13 hits, and only one--a lone homer--going for extra bases. Miller managed to hold same-handed hitting to a .149/.245/.184 batting line. There were only nine pitchers more effective against lefties than Miller last year.
That's right, Andrew Miller is top-10 in something positive again. It's like it's 2006 all over again!
A LOOGY is not the most valuable player on any roster. Their role is by definition limited, and come the end of the year they're likely to have seen fewer plate appearances than anyone shy of the fifth outfielder who stayed with the team all year long. But there are plenty of dangerous lefties out there who nobody wants to see come to the plate against their team late in a close game. If Miller can actually keep up that sort of production against lefties, or even come close, then he's a guy who can stick around on most teams by the merit of that ability alone.
Whether he can stick with the Red Sox is another story. The bullpen is loaded, and has a few good lefties in Breslow and Morales (who moonlights as starting depth). That being said, whether it's in Boston or elsewhere, after 2012 Miller will at least know there's a role he can play.