Charlie Fliegel: Nats bullpen is missing effective left-handed specialist

The Nationals bullpen has been overused the last week, thanks to short stints from starting pitchers. However, since the addition of Mark Melancon, most of the title-worthy roles appear to have stabilized in the 'pen. Except one spot seems to be missing, and it's a need they must address.

Melancon is, of course, the closer. Shawn Kelley seems to have nabbed the role of setup man. Since the beginning of July, he's only given up four earned runs in 20 appearances, held opponents to a .269 on-base percentage and has struck out 23 in 16 1/3 innings. On the season, he ranks seventh among all pitchers in strikeout rate, ahead of Aroldis Chapman.

Right on his heels is the seventh-inning guy, Blake Treinen. Treinen actually has better ERA than Kelley, has done an excellent job of keeping the ball on the ground and hasn't allowed as many home runs. But besides his lower K/9 rate, Treinen is walking too many to steal Kelley's role. Yusmeiro Petit has the other named job as the long man, and he's done all right when put in that particular role.

In general, the bullpen has been effective over the course of the season. You can quibble over where it ranks, but leading all of baseball in ERA through Aug. 23 is a pretty good indication of success.

What is missing from this collection, though, is a lefty specialist. The closest thing they have right now is Oliver Perez, and he isn't that close right now. Lefties are hitting .225/.325/.395 off of him, which just is not good enough.

There may be a bad break here or there - one fewer home run and the OPS drops to .650. If he can get the next four lefties he faces out, the OPS drops to .619, the OBP to .299. But he has looked ineffective, not unlucky.

On the other hand, lefties hit .185/.235/.283 against him in 2015. This history, the ability to have decent numbers with just a few good outings and the Nats' eight-game division lead may combine to afford him some more chances. But if he can't get there, it probably is the biggest hole they've got to fill before the postseason.

First, they should look to their current bullpen to address the issue. Ranking them by wOBA vs lefties, it seems like Sammy Solis is their best option as a lefty-killer. This would be the easiest fix, except he's on the disabled list right now, so that only works if he comes back healthy. You'll notice Matt Belisle's numbers are great this year, but the righty does not have reverse splits for his career. He's usually decent against lefties, but nothing special. This year is an outlier that is probably not a sign of new effectiveness against them.

Within the rest of the organization, they do have a few options, starting with the newly reacquired Sean Burnett. The once and future Nat hasn't pitched much in the majors since leaving Washington in 2012 thanks to injury, but he's been effective throughout his career against left-handed hitters. Pitching in Triple-A this year, they have only slashed .190/.226/.259 against him.

Another option is Matt Grace, who has allowed .203/.212/.266 from lefties this season, also in Triple-A. He was up briefly with the Nats in 2015, when he was hit hard, but mostly by righties - he wasn't great against them, but he was better against lefties than Perez has been this season.

One more in-house option is Bryan Harper, who has earned his way up to Triple-A through his effective pitching, especially against lefties. This season, they are hitting a minuscule .125/.211/.172 against him, and, although this is not exactly what we'd expect over a longer timeframe, or in the majors, he's been effective against lefties throughout his career.

Neither Harper nor Burnett is on the 40-man roster, while Grace is, although there is room for another player without making another 40-man move. All of these guys have good numbers this year, none of it in the majors.

There is another possible option against lefties come playoff time, and that is Gio Gonzalez. Depending on the composition of the opposing lineup, he may get starts against lefties, who are hitting .214/.290/.321 against him. But if he doesn't start, he may be the best option they have out of the bullpen.

As long as Perez struggles, the Nats don't have a lefty specialist. But they have some options, and they should spend September exploring them.

Charlie Fliegel blogs about the Nationals for The Nationals Review. Follow him Twitter: @nationalsreview. His thoughts on the Nationals will appear here as part of MASNsports.com's season-long initiative of welcoming guest bloggers to our site. 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.