Ryan Romano: If Hart fares better vs. righties, he'll have a shot in O's bullpen

While the Orioles have one of the best left-handed relievers in baseball -- and one of the best southpaws, period -- in Zach Britton, their bullpen skews to the right overall. Brad Brach, Mychal Givens, and Darren O'Day each throw right-handed, and they've all had some problems with lefties, albeit to vastly different extents. With Brian Matusz melting down and hitting waivers, Baltimore has tried out a host of left-handed bullpen arms to see if any of them can stick, and most (Ashur Tolliver, Brian Duensing, and Ariel Miranda, among others) have flopped. Thus far, however, Donnie Hart has not. He has yet to allow a run through 9 1/3 innings, and he's shown an ability to retire lefties, tallying six strikeouts and one walk against the 25 he's faced, en route to a .227 wOBA.

But that success has not carried over to right-handed batters. Of the 13 righties to step in against Hart, three have worked a free pass, and only one has gone down on strikes; as a result, they have a .334 wOBA off him. Lest you attribute this to small sample sizes -- and, in fairness, these plate appearance totals are rather minuscule -- the disparity exists on a pitch level as well. According to Brooks Baseball, Hart has thrown 66.0 percent strikes and 9.6 percent whiffs to lefties, and 52.5 percent strikes and 7.5 percent whiffs to righties. If his troubles against opposite-handed batters don't dissipate, Hart will stay in a limited role in the bullpen.

We can say, with some degree of certainty, that Hart will always have a platoon split -- in other words, that righties will always hit him harder than lefties. As research in The Book illustrated, this is a characteristic of virtually all side-armers, especially those with an arm angle as low as Hart's. That doesn't mean he has to struggle when pitching to right-handed hitters, though. Look at O'Day: He owns a lifetime wOBA of .249 against righties and .301 against lefties, but the latter is still much better than average. Hart doesn't need to blow righties away; he simply needs to be able to get them out when they come up, so that he can mow down the lefties he sees.

Accomplishing that will require an offspeed pitch, the best offering for attacking opposite-handed hitters. Hart has one, a changeup -- and it looks like a pretty good one. Baltimore Sports and Life's Reggie Yinger, who worked in player development for the Orioles when they drafted Hart, evaluated the southpaw's arsenal in the offseason. He argued that the changeup was "easily his best secondary [pitch]," owing to the "nice sinking motion" it generated. That characteristic has made the leap to the majors: Only four other changeups in baseball, among the 576 pitchers who have used one this season, have more drop than Hart's 3.5 inches.

But vertical movement is the only thing Hart's changeup brings to the table at this point. He hasn't thrown it for strikes that often -- its 60.0 percent strike rate falls below the strike rates of his sinker and slider -- and opponents have hit it fairly hard, collecting three of their eight hits overall on the changeup. Hart has really struggled with controlling the pitch; out of its 20 appearances this season, just once has it landed in the strike zone. Per FanGraphs' Pitch Type Linear Weights, the changeup has been the only negative offering in Hart's repertoire. Without the offspeed pitch to retire righties, Hart will remain the Lefty One-Out Guy for the Orioles.

September will come in a few days, which means major league rosters will expand from 25 to 40 players. That could lead to fewer opportunities for guys like Hart, as other minor-league arms get a shot. Thanks to his sinker/slider combination, Hart has excelled against lefties, but righties haven't gone down as easily. If he wants to remain in the Orioles bullpen mix, he'll have to set down hitters of either handedness, and his cambio will have to spark that progress.

All data as of Monday, August 29th.

Ryan Romano blogs about the Orioles for Camden Depot. Follow the blog on Twitter: @CamdenDepot. His thoughts on the O's appear here as part of MASNsports.com's continuing commitment to welcome guest bloggers to our little corner of cyberspace. All opinions expressed are those of the guest bloggers, who are not employed by MASNsports.com but are just as passionate about their baseball as our roster of writers.