Haren lasted four innings and allowed five runs, all the result of a trio of homers. Haren was given a 1-0 lead in the first inning, when Ian Desmond swung at a Dillon Gee pitch and singled to left field, scoring Denard Span.
But it was all Mets after that. New York took the lead in the top of the second inning, when Marlon Byrd hit a two-run homer.
"Haren was struggling hitting his spots. To me, it looked like his pitches were a little flat," manager Davey Johnson said. "When he throws that many pitches, you know he is having some problems locating the ball."
Haren was unable to contain the Mets in the next inning as David Wright hit a two-run homer, and two batters later, Byrd hit his second home run of the game to make it 5-1.
Although he hit two home runs against Haren, by no means did Byrd think it was easy facing the right-hander.
"Oh gosh, Danny's tough. I've been facing him since [he was in St. Louis]," Byrd said. "I know you have to be focused when you go up there. I just got two pitches to hit tonight and didn't miss them. Usually he's down in the zone with his split-finger and down in the zone with his slider, down and away. So he just left a couple pitches up tonight, and I put good swings on them."
Haren was the antithesis of his previous start against the Orioles. In that game, Haren allowed two runs in 7 2/3 innings.
As his custom, Haren didn't make any excuses for his disappointing outing. He insisted that he is healthy and ready to make his next start.
"It's very disappointing, obviously," Haren said. "I feel bad for the guys. I let them down. I'm the same guy that I was five days ago. [In Baltimore], I went through one of the toughest lineups in baseball. I laid another egg tonight. I have to be better. I got to pick it up for these guys. No one feels worst about it than I do. But what can I do?"
Haren has been in the big leagues since 2003, and he has never had a year like this one, in which the consistency he is used to having is missing.
"I feel good one day and so bad the next. Body-wise, I have no excuses. I'm healthy. If I feel something, that would be an easy way out. … I'm just not getting the job done," Haren said.
Craig Stammen came on in relief and had a forgettable outing, allowing two runs on single to Anthony Recker in his inning.
Left-hander Ian Krol made his Major League debut and was solid, striking out the side in the sixth. Krol acknowledged that he was nervous. His fastball was clocked as high as 95 mph.
"I didn't take a breath until the seventh inning," Krol said. "The whole scenery and everything is different. It's crazy. It still hasn't sunk in yet. To be honest with you, I'm still on cloud nine. Hopefully, later, when I get into the bed, go to sleep and it all settles down, the nerves will go away. We'll see."
The Mets added three more runs against right-hander Erik Davis in the top of the seventh inning. Recker highlighted the scoring with a two-run double.
Gee had one of his best games of the season, pitching seven innings and allowing the one run on nine hits.
"We hit a lot of balls hard right at people, but he made pitches when he needed to," Span said. "He seemed to have kept the righties off-balance with his slider. He did a good job."
The Nats had a chance to score more than one run off Gee. In the bottom of the fourth, the Nationals had runners on second and third with one out, but Span and Jayson Werth struck out to end the threat.
"We haven't played good -- I'm going to be honest -- all across the board," Span said. "We let a lot of opportunities go by tonight. Second and third and one out, we got to get those runs in and we didn't do it. And after that, [the Mets] just went off."
For the game, the Nationals went 2-for-13 with runners in scoring position.
"We just turn the page on this one," Johnson said. "We swung the bats better, but we had runners in scoring position. We could have made it closer."