The Nats pitchers are the reason the Nats are as successful as they have been. You can toss in Bryce Harper in there if you like and maybe Adam LaRoche* but beyond that it's all about the pitching. Hell they've even done some carrying at the plate.
The Nats pitchers are hitting .200 / .226 / .300 for an OPS of .526. OK that's certainly not good, but it's not terrible for the pitcher spot. Since 2003 only two teams (the 2008 Cubs and the 2010 Brewers) have had staffs hit over .500 OPS. Their 5 doubles lead the league. Their 2 homers lead the league. They are hitting as well as Mike Morse has been this year. Much better than Xavier Nady.
It's one thing to say your pitching staff is not the worst but everything in baseball has to be looked at in comparison to everyone else. The next best staff is hitting .161 /.179 / .203 for an OPS of .382. That's a huge difference. Looking at fancy stats like wOBA and wRC+ what it comes down to is the Nats staff is like a very bad part-time player, among the worst in the league. But the other teams staffs are like players that would be struggling in AA. The other teams pitchers are basically automatic outs, the Nats pitchers can't be ignored in the same way. It's a little difference in the long run but little differences can add up. When the playoffs are a matter of a game or two, having a set of pitchers that can hit is something that can maybe make up that difference.
Of course with a different guy hitting every day some guys will be doing well and other guys are as bad as everyone else. Who are the ones that really need paying attention to?
Strasburg : .350 / .381 / .650
ZNN : .318 / .348 / .500
Edwin Jackson : .160 / .160 / .160
Why include Edwin? Well unlike Strasburg (alot) and ZNN (a little), Jackson isn't propped up by a high BABIP. And he hit well last year too (.267 / .281 /. 267). I think he fits the bill of can't being ignored. Are Strasburg and ZNN going to keep those paces up? Of course not. But Strasburg has taken to hitting rather well considering he hadn't done it since high school. ZNN has a very favorable K% rate for a pitcher and has his entire career. He is going to put the ball in play.
One of the keys to success in the NL for pitchers is being able to dominate the pitcher spot. You sort of locate a couple fast balls, throw an offspeed pitch and move on to the real batters. Gio Gonzalez has done this. Pitchers are 0-21 against him with SEVENTEEN strike outs. Strasburg too (0-21 with 14K). Against at least these three starters - pitchers have to at least think about what they are doing and it has to make a difference.
*The state of 1B in the NL has taken a dive with the loss of Pujols and Fielder. The 2nd-4th best hitting first basemen so far this year in the NL are Bryan LaHair, LaRoche, and Paul Goldschmidt. After that it's Todd Helton who's hitting .242 / .338 / .434. He ranks 42nd in the NL in OPS. For a position that should be able to be filled by any oaf who can swing a bat the NL teams are having a tough time finding oafs.