The Mets' Brandon Nimmo gestures after hitting a grand slam...

The Mets' Brandon Nimmo gestures after hitting a grand slam off Washington Nationals pitcher Cole Henry during the seventh inning of a game in Washington on Monday. Credit: AP/Terrance Williams

WASHINGTON — One small blemish on the Mets’ rousing start to the season has been a slow start by some key hitters, such as Brandon Nimmo.

Considering the Mets’ record, it’s a bit like a pimple on the Mona Lisa. And, according to manager Carlos Mendoza, Nimmo’s struggles going into Monday’s series finale at Nationals Park were a bit perplexing.

“He’s not getting results [but] he's hitting the ball hard, you know?” Mendoza said. “It’s kind of weird.”

Maybe it was also nothing at all to be concerned about. Nimmo went 4-for-6 with his second career grand slam, a three-run home run, a two-run double and a career-best nine RBIs as the Mets earned a split of the four-game series with a 19-5 victory.

“It was really fun to play today,” said Nimmo, who tied the franchise record for RBIs set by Carlos Delgado in 2008.

“He's a good hitter,” Mendoza said of Nimmo. “You know at some point those guys are going to come out of it. It's part of a big-league season where at times is going to be hard, and then you'll see games like this. Hopefully, we started seeing the Nimmo that we all know. Pretty good player, and it was good to see him go out there and have that type of performance.”

Jeff McNeil hit his first home run of the season, the Mets banged out 21 hits and Griffin Canning continued his fine early-season work with five shutout innings as the Mets improved to 20-9.

 

With the Mets leading 15-5, Nationals manager Dave Martinez had former Mets infielder Amed Rosario pitch the ninth. The Mets scored four more runs, including a three-run home run by Mark Vientos on a 53-mile per hour offering with Nimmo on deck.

“I was thinking like, ‘Oh, man, be really cool to get double-digit RBIs in a day’ when I was coming up, possibly, before [Vientos] hit the three-run homer,” said Nimmo, who grounded out to second. “I was like, ‘Oh, man, this would be sweet to get a couple more out of it.’ ”

Nimmo went into the game batting .192 with four home runs and 12 RBIs. He was slotted sixth in the order against former Mets righthander Trevor Williams.

After dropping two of the first three games of this series in walk-off fashion — including Sunday’s 8-7 loss after the Mets had a 7-1 lead in the seventh inning — you could excuse the Mets if they were hoping for an easy victory on Monday.

That’s what they got. Nimmo’s first blow to right-center on a 2-and-0 pitch from lefthander Colin Poche in the sixth doubled the Mets’ lead from 3-0 to 6-0.

In the seventh, Nimmo connected off righthander Cole Henry, also to right-center, for a grand slam on the first pitch of the at-bat. That made the score 11-0. It was Nimmo’s seventh career multi-homer game.

The Mets sent 11 batters to the plate in their five-run seventh. Henry hit Francisco Lindor with a pitch to start it. When the lineup turned over, Henry again hit Lindor with a pitch.

In the eighth, Nimmo again came to bat with the bases loaded. The many Mets fans in the small crowd of 14,011 rose up, looking for a second grand slam. Nimmo lined a two-run double down the rightfield line. The rout was more than on after Sunday’s bitter defeat.

“We definitely understand that we were very close to at least taking three if not trying to sweep the series,” Nimmo said. “But you know what? It's baseball. It happens. Sometimes we're not going to be perfect. So you try and flush it and come back today. And I thought the guys did an amazing job with that.”

The Mets took a 2-0 lead in the second on an RBI double by Francisco Alvarez and a sacrifice fly by McNeil (2-for-5, three RBIs). McNeil’s home run on the first pitch of the fifth made it 3-0.

Canning (4-1, 2.61 ERA) allowed four hits, walked three and struck out five.

James Wood and Nathaniel Lowe hit solo home runs off Jose Urena in the eighth. Urena, who was making his Mets debut after getting called up on Sunday and had thrown a perfect seventh, gave up five runs on seven hits in the eighth.

Mendoza had Urena pitch the ninth, and the righthander finished the job and was credited with a three-inning save.