The recently departed Matt Capps will be missed. He had a strong July, leading the bullpen in K/BB and FIP, and ending up second in xFIP. His season K/BB and xFIP were each 2nd on the team. His 26-4 SV-BS and 2.74 ERA also look nice.
Either Sean Burnett or Drew Storen is now the best pitcher in the bullpen with Tyler Clippard not far behind. All three are benefiting from low HR/FB% (Storen has yet to allow a home run), though they are also each sporting 2+ K/BB ratios. Look for Clippard to have an improved August after his bad luck in July (.338 BABIP, 46.9 LOB%) left with an ugly-looking ERA of 7.90 for the month and one blown save for good measure.
Miss Iowa himself Miguel Batista had an ugly-looking July ERA (6.30) driven by a .411 BABIP allowed. His FIP (4.71), xFIP (3.62), K/BB (3.67), and start looked much, much better.
Forgotten man Doug Slaten continues to give good performances (4.16 FIP, 4.06 xFIP in July, 3.75 FIP, 4.71 xFIP season) for the Nats and has been rewarded with a spiffy 3.68 ERA on the season.Recently recalled Collin Balester pitched well in his 3 innings in July. His career numbers (1.72 K/BB, 4.99 xFIP) are not so good, though. He is also into mustaches.
Joel Peralta's 2.01 ERA looks great but it seems to be the result of luck. His .207 BABIP and 94.9 LOB% are nowhere close to being sustainable. I think his xFIP of 4.46 gives a much clearer picture of where his ERA "should" be.
With the ensuing battle for closer, the acquisition of potential relievers Joe Testa, Tanner Roark, and Ryan Tatusko, and the general reshaping of the Nats bullpen, August should be a great month to follow the Nats relievers-at least for guys like me who are into that kind of thing.