NEW YORK -- Here’s one of the major issues preventing a turnaround for the Nationals’ bullpen: Whenever a reliever starts stringing together scoreless relief appearances, he is almost immediately elevated into the next high-leverage situation regardless of previous workload. It’s a product of how few reliable options are available for manager Dave Martinez, and perhaps it’s an indictment of how he is utilizing his relievers to navigate through the late innings of a game.

The moves Martinez made attempting to seal Tuesday night’s game at Citi Field largely backfired, as Washington’s bullpen imploded yet again, squandering leads in the seventh and eighth innings, paving the way for Amed Rosario to beat out an infield single in the ninth to send the Nats to a 6-5 walk-off loss to the Mets.

“It’s frustrating. It really is,” Martinez said. “The guys are battling. But we’ve got to finish games. It’s a nine-inning game. We’ve got to start finishing games. We’re right there, but we’ve got to win. The bottom line is we’ve got to start winning games.”

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Tuesday night’s game played out like many before it this season for this beleaguered Nationals bullpen, with their offense putting them ahead several times before their relievers gave the advantage back. Wander Suero, Tony Sipp, Matt Grace, Tanner Rainey and Kyle Barraclough all pitched in a tight game on the road against a division opponent. Sean Doolittle did not.

Suero was the first reliever summoned from the bullpen by Martinez to pitch the sixth inning of a 1-1 game. Despite the unsightly 6.20 ERA, he has developed into one of the Nats’ most reliable options, allowing one run in his previous seven appearances entering Tuesday with 11 strikeouts and one walk. However, he also threw 30 pitches in a two-inning stint Sunday night, and yet after a scoreless sixth inning Tuesday, Martinez pushed him for a second frame.

Then, Suero hung a curveball in the seventh inning to pinch-hitter J.D. Davis, who smashed it for a three-run homer. Suero’s curveball is perhaps his third-best pitch, and Davis is batting .429 this season on breaking pitches. But it was what catcher Yan Gomes called on a 1-2 count and it got left over the middle of the plate.

“I mean, again, he got two big strikeouts with it,” Gomes said. “We were trying to expand the zone with it and just when you leave pitches up to good hitters, they're going to do some damage to it.”

The Nationals bailed out Suero with a pair of runs in the eighth inning to take a 5-4 lead, and after using lefty Matt Grace to retire lefty Robinson Cano, Martinez turned to Rainey to face Mets rookie sensation Pete Alonso.

Rainey tossed a 13-pitch scoreless inning the night prior in what was just his ninth career appearance in the big leagues, and he was tasked with pitching to the Mets’ best hitter with the game on the line in the eighth inning on Tuesday. Rainey missed with a fastball over the middle of the plate and Alonso hammered it over the foul pole in left field for a game-tying solo homer.

“I liked Rainey a lot in that situation,” Martinez said. “He’s throwing the ball really well. And I knew that when we got him. They said he was really throwing the ball well. And he did. He gave up the home run. I know what he was trying to do. He was trying to get the ball up 1-2. Didn’t quite get it up enough.”

Rainey retired the next two batters to escape the eighth inning with the game tied, but Martinez decided to extend him for the ninth inning as well. Yes, Martinez considered using Doolittle in a tie game, but he decided against it rather than burn the closer in case the game went to extra innings. That scenario never occurred.

Instead, he stuck with Rainey, who walked 12 batters in 16 games this year at Triple-A Fresno and whose control problems plagued the Nats once again. He issued back-to-back two-out walks and threw 33 pitches before he was finally lifted from the game. Barraclough, who had allowed seven of eight inherited runners to score entering the outing, could not escape the inning unscathed and sent the Nationals to their third straight loss.

At the start of this series, it was New York who was seemingly in trouble, losers of five in a row with question marks surrounding the job security of the manager. Now Washington has dropped back-to-back games to start the series. The loss dropped the Nationals to 19-29 on the season, a season-low 10 games under .500. It’s the first time they have been that far below .500 since September 11, 2011, before they won their first National League East title.

“I think mostly the seventh, eighth innings start happening or when those runs start coming in we -- I mean you definitely see a drop,” Gomes said of the team’s psyche. “I think it's one of those things man, because we do come out and battle and battle and battle. I think it kind of gets tiring to say we just need that one hit, just need to make it happen more than just wait for it to happen.”