They had finally gotten a starting pitcher, Jacob deGrom, into the eighth inning of a game.

It was a luxury that would seemingly afford the Mets bullpen, which has been averaging 12 outs per game, a rare night of rest.

Todd Frazier, signed as a free-agent in the winter, had continued his strong form at the plate, driving in two runs. And Asdrubal Cabrera, who was not sure he even wanted to be here last June, continued to hit as if there were nowhere he would rather be than at Citi Field.

And most important, the Mets were five outs away from posting their fourth win in four early-season games against the Washington Nationals, the preseason favorites to win the National League East title — a win that would give the Mets a seven-game cushion atop the division.

Then deGrom left, and what had seemed destined to be a statement game for the Mets turned into a nightmare.

DeGrom, who had struck out 12 and limited the Nationals to six hits — one of them a memorable broken-bat home run by Bryce Harper — gave way to a procession of relievers who just could not put away a Nationals lineup that was missing three of its most potent bats.

Seth Lugo, Jerry Blevins, AJ Ramos and Jeurys Familia struggled to get the final two outs of the eighth inning, and by the time they had, the Nationals had pushed six runs across the plate to turn a comfortable 6-1 Mets lead into a 7-6 deficit on the way to an agonizing 8-6 loss.

To add a final insult to their injury, Cabrera squandered a chance at a ninth-inning rally by trying to stretch a one-out double into a triple, and was thrown out at third.

“It’s one inning. It’s not even a whole game,” manager Mickey Callaway said. “It’s really just one inning. We outplayed them for the rest of the game. We’ve got to make sure this doesn’t throw us into a tailspin because we’re a really good team and we’ve been showing that.”

It was a game that featured both the Mets’ expected preseason strengths — superior starting pitching and timely hitting — and one of its most pressing worries: the bullpen.

Apart from Harper’s first-inning homer, a 406-foot blast into the Mets bullpen hit with a bat that snapped on contact with the 96-mph fastball, deGrom had tamed a Nationals lineup that was without Daniel Murphy, Anthony Rendon and Adam Eaton.

Playing without Jay Bruce, who a had flare-up of plantar fasciitis in his left foot, and Yoenis Cespedes, given the night off, the Mets answered Harper’s home run with six unanswered runs.

Frazier, who is batting .313, singled in one run in the bottom of the first and doubled in another in the third. The Mets added two more in the sixth without getting a hit, and then Cabrera, hitting .356 with a 1.041 on-base-plus-slugging percentage, belted his fourth home run of the season in the seventh to make it 6-1.

But once deGrom left the game, having allowed two singles, it all caved in on the Mets.

Lugo walked Howie Kendrick to load the bases. Callaway then called upon Blevins, his left-handed specialist, to face the left-handed hitting Harper. That resulted in a two-run single, a lead cut to 6-3, and another call to the bullpen, for Ramos. He began well, striking out Ryan Zimmerman, but allowed a single to Pedro Severino, loading the bases once again. Ramos then walked pinch-hitter Matt Reynolds to force in the Nationals fourth run of the game.

That prompted Callaway to bring in his closer, Familia, who surrendered a single to Wilmer Difo, bringing home two more runs and tying the game. With no one up in the pen, Callaway was forced to stay with Familia, who hit Moises Sierra with a pitch, loading the bases yet again, and then walked Michael Taylor, forcing in the go-ahead run. The inning only ended because a screaming line drive by Trea Turner happened to be hit right at Mets left-fielder Michael Conforto.

The Nationals added their eighth run on a solo home run by Kendrick off Hansel Robles leading off the ninth.

The bullpen meltdown left Callaway searching for answers to what went wrong with a relief corps that has been nothing but reliable through the first 14 games of the season.

“The only thing I can think of is, when you have your starting pitcher who’s just dealing like that and he goes out for the eighth, it shouldn’t happen, but maybe guys kind of shut down a little bit mentally,” he said. “And then all of a sudden, things get out of control and the next thing you know, they’re in a game they thought they had no chance of pitching in. It’s 6-1 in the eighth, maybe they relaxed a little bit.”

This article originally appeared in The New York Times.

WALLACE MATTHEWS © 2018 The New York Times