Why the Nats Don't Need a LOOGY
For those unaware a LOOGY is a Lefty One-Out Guy, essentially a left handed reliever whose sole purpose is to come in and get dangerous left handed hitters out in the late innings. Carrying a LOOGY is a fairly common practice in Major League Baseball. Last season the Nationals carried such a pitcher in reliever Michael Gonzalez, who was an excellent .179/.257/.269 against left-handed batters.
This season the Nationals have no such pitcher on the current roster, with only one left-hander, long man Zach Duke, in their bullpen. While many have wondered how they will fix this "problem", such as re-signing Gonzalez before he signed with the Brewers or picking up free agent JP Howell, many have ignored that there is no problem at all. The Nationals have no need for a LOOGY.
As I said above Gonzalez had a great season against left-handed hitters last season, but unlike most LOOGY's he wasn't used exclusively against left-handed batters. In fact, he was used in more plate appearances against right handed batters (76 vs. 75 against LHB), who he was an atrocious .297/.378/.484 against. His fellow left-handed bullpen members: Sean Burnett (144 RHB vs. 95 LHB); Tom Gorzelanny (177 RHB vs 129 LHB); and Zach Duke (40 RHB vs. 16 LHB) have similar splits between facing left and right handed batters. While this is somewhat explainable for the other three as their roles in the bullpen required them to face right-handers by necessity, this isn't true for Gonzalez. Clearly the Nationals, or at least Davey Johnson, don't believe in using lefty relievers as lefty specialists.
On top of that the right handed relievers the Nationals do have are excellent against left-handed batters, most even better than supposed top target Howell. Here are the triple slashes of left handed batters against the top Nats relievers: Tyler Clippard (.186/.268/.325 career); Drew Storen (.229/.287/.297 career); Ryan Mattheus (.214/.294/.393 career); and Craig Stammen (.198/.274/.331 in 2012, his first season as a reliever). Compare that to Howell, and his .241/.323/.351 line and you can see that the Nats are perfectly fine with the relievers they have.
While the Nationals do need another reliever, unless they decide to keep Christian Garcia in the bullpen, choosing one based solely on a perceived need for a left hander would be foolish. The Nats don't use lefties to their platoon advantage, and as it is they already have talented right handed relievers who perform better than the top lefty relievers available. The Nats should focus on getting the best reliever available, not on filling some left handed quota.