In 2010, the Nationals were last 12th in the NL in overall runs allowed per game at 4.58 (league average was 4.35). The starters were 14th in the league with an ERA of 4.61, while the relievers were 4th at 3.35--even though they pitched more innings than any bullpen in the league.
This season, the Nationals' runs allowed per game are down to 4.07 (before tonight's game against Milwaukee). The bullpen has improved on their excellent 2010 performance, lowering their collective ERA to 2.97. But the really big improvement has been with the starting pitchers--they've cut their ERA by more than half a run to 4.05 while pitching 6.07 innings per game, a huge and very much needed improvement from the awful 5.49 innings per start last season.
But the reality is that a lot of that improvement is a function of the dramatic drop in scoring league-wide--NL runs per game have fallen from 4.35 to 4.13--the lowest since 1992.
That's not to take anything away from the team's accomplishment rebuilding the pitching staff. Remember what a disaster the bullpen was when Mike Rizzo took over. And he's made some savvy moves to upgrade the rotation--in particular flipping 5 o'clock slugger Mike Burgess for Tom Gorzelanny and signing Jason Marquis to a reasonable two-year deal that is finally paying dividends.
Still, allowing 4.07 runs per game just isn't what it used to be. In 2009, that would have been good for 5th best in all of baseball, just .01 behind the San Francisco Giants staff led by Matt Cain and Tim Lincecum. As good as the starters have been, they don't have anyone in the top 50 qualified starting pitchers for xFIP--Jordan Zimmermann is the best at #57.
That's a big part of why, for all their seeming progress, the Nationals after tonight's loss to the Brewers are 21-26, a .447 winning percentage that puts them on pace for just 72 wins, and for that matter why things are very unlikely to get better any time soon.