It wasn't hard to find the turning point of the Mets' 8-2 loss to the Nationals Thursday night at Citi Field.

It was an error by shortstop Wilmer Flores on a routine double-play ball that unnerved Jacob deGrom and led to a three-run fourth inning.

The loss was the Mets' first at home in 11 games this season. They have dropped five of seven after an 11-game winning streak.

They finished April 15-8 -- a great start to the season. But they may have a problem at shortstop, where Flores is playing down to his reputation with six errors. DeGrom, who retired the first nine Nationals before unraveling after the error, admitted he let it get to him.

"That was frustrating," deGrom said of his outing. "Felt like I had good stuff. There were a couple times -- the walks and stuff like that -- I got a little frustrated."

Asked if his location was the problem, deGrom made it clear what he thought the problem was by bringing up Flores' error without any prompting.

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"I don't think so," he said. "I didn't give up many hits to begin the game. I've got to do a better job of picking Flo up on that play right there . . . Normally I do a pretty good job of that. I think I was doing too much. I think I was overthrowing."

DeGrom was a completely different pitcher before and after the miscue.

Before the error: 10 batters faced, the first nine retired, one walk, Mets leading 2-0.

After the error: 13 batters faced, five hits, one walk, five runs, Mets trailing 5-2.

"Certainly, it changed the tide," manager Terry Collins said. "No question about it . . . He couldn't get out of it. It might have disrupted his thought process, his tempo a little bit, to think he's got to now be perfect. I don't know. It certainly was obvious that it didn't help."

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With the Mets leading 2-0 on an RBI double by Kevin Plawecki and an RBI single by Curtis Granderson off Stephen Strasburg (2-2) in the second inning, deGrom (2-3) walked Denard Span to open the fourth.

Yunel Escobar followed with an easy double-play grounder to Flores, who had it bounce off his glove. "He just missed it," Collins said. "He just dropped it."

Flores said he rushed the play. "I should have caught it first," he said. "That's what your pitcher's looking for -- being able to execute."

Jayson Werth singled in a run to make it 2-1 before deGrom walked Bryce Harper to load the bases. "The four-pitch walk to Harper," deGrom said. "That kind of tells you that I was frustrated there instead of going right after him and getting another double-play ball."

Ryan Zimmerman's sacrifice fly to center tied it as all three runners moved up a base. Then, with the infield back, Wilson Ramos grounded out to Flores as the go-ahead run scored.

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DeGrom, who allowed five hits and five runs (three earned) in 5 1/3 innings, was knocked out in the sixth as the Nationals scored two more runs on four hits. Harper added a three-run double in the ninth.

Herrera called up. After the game, the Mets announced the recall of second baseman Dilson Herrera on Friday. Herrera, 21, was batting .370 for Triple-A Las Vegas. He may play second with Daniel Murphy moving to third while David Wright is out.