Last season around this time, some local sportswriters were waxing eloquent about how perfectly balanced and "fair" (some might have said vanilla) Nationals Park is. The stadium was playing neither as a hitter's park nor as a pitcher's park but a pretty much down-the-middle even ballpark favoring neither.
But it takes at least two or better yet three seasons of play to get a large enough sample size to identify a park as favoring hitters or pitchers. And this year Nationals Park is acting like one of the league's most pitcher-friendly parks.
ESPN.com posts park factors for a series of stats--overall scoring, home runs, hits, etc. Park factor is a pretty simple stat. You take the number of runs (or HR or whatever) that a team has scored at home, divide that by the what they've done on the road (weighted by games played), and voila, you have PF.
The overall runs scored PF at Nationals Park this year is .915, 24th in the league, more pitcher-friendly than famed pitchers' parks CitiField, Comerica, or the Oakland Coliseum. RFK's single-year PFs were .874, .942, and .860 in '07, '06, and '05, respectively. Yes, that's right, Nationals Park in 2009 has been more of a pitcher's park than RFK was in 2006.
I don't actually think Nationals Park favors pitchers as much as it would seem so far this year. Again, 60 or so games just isn't enough of a sample size to draw firm conclusions. Personally, I thought if anything Nationals Park would emerge as more of a hitter's park this year, figuring that Adam Dunn might give them enough lefty thump to start to expose the short porch in left.
So we should give it another year, but it's worth noting that so far this year we're getting a really different picture than most anyone expected going into the season.