Okay, we're 30 games past half-way, but it's never too late to review the stats. Let's take a look:
Overall: D-
The Nationals are 50-66 right now, with 470 runs scored and 534 runs allowed. They're last in the NL East, 8 games behind the 4th-place Marlins, 13th in the NL, and 15.5 games back from a WC spot. On the other hand, they're only 0.6 runs per game below average by "simple rating system" (a scheme that rates a team by average run differential weighted by strength of schedule--and the Nats play in a tough division), which is good for 11th in the NL. It's better than last year, but it's still firmly in the cellar. Not a fail, but not by much.
Grades for Batting, Fielding, Pitching, and Luck after the jump. Stats courtesy of baseball-reference and fangraphs through games of 8/13/10.
UPDATE: I've been called me out for harsh grading and reminded that the team is better this season. I agree, but last place is still last place. And I was much harder on them last season.
Batting: D
The team's average slash stats are 256/322/400, slightly below the league average of 257/326/402. The team is slightly above average in HRs (109 vs. NL average of 108), although they are third in triples, with 26 (tied with the Fillies, and behind the Mets' 30 and Colorado's 34). The team is 3rd in SB (86), but also in CS (32). But the real pain is what it adds up to: the Nationals are only scoring 4.05 runs per game, third from last in the NL (average is 4.39).
Fielding: C
I know, the errors have been painful and lead the league (92). However, the advanced metrics (total zone runs, defensive runs saved, ultimate zone rating) bracket league average. Some, like revised zone rating and out-of-zone plays are solidly above league average. We've all see this ourselves: great rangy plays on difficult batted balls, offset by bad throws, missed cutoff men, and booted DP grounders. Overall it's a wash.
Pitching: C-
The Nats are giving up 4.60 runs per game, 11th in the league and a bit below league average (4.43). Despite Strasburg, the team is second to last in K/9 (6.5), although only 8th in BB/9 (3.3). Team ERA+ is exactly league average at 100 (ERA+ adjusts ERA for ballpark effects). Team FIP is 4.10, 10th in the league. Starters are going 5.5 innings per game, 2nd worst in the NL. Nats relievers are allowing 32% of inherited runners to score, right around league average. Their save percentage is 66%, just below league average. Washington has only 4 shutouts this year (2nd worst) and 2 complete games (tied with a bunch of teams for 13th). Average performance, but below average peripherals.
Luck: Neutral
This doesn't count in the GPA--it's like the mark for citizenship. The Nats' overall record is one game worse than its expected record (51-65) based on its run differential (slight bad luck). Team BABIP is .299, which is right around average--no particular good or bad luck on hits finding gloves or open grass. The team's pitchers strand runners at a rate of 70.1%, also neither lucky nor unlucky. Opposing batters' BABIP is .309, which is slightly unlucky. At the same time, the team ERA (4.14) is almost the same as team FIP (4.10), which is neutral, but the team FIP is noticeably less than team xFIP (4.41), which indicates a little bit of luck in the number of flyballs that turn into dingers. Overall, the Nats' performance has reflected its talent, not its luck.