The Mets dealt away a pair of three-time Cy Young award winners and a former All-Star closer at the trade deadline. Tuesday’s excruciating pitching performance isn’t going to generate trophies or superlatives for any of the participants.

Starting pitcher David Peterson — back in the rotation following the white-flag trades of co-aces Max Scherzer and Justin Verlander and closer David Robertson, among others — and two of the four relievers used combined to walk a season-high 10 batters in the Mets’ 7-4 loss to the Pirates at Citi Field.

“We walked, what, 10 guys tonight? We hit two guys. I’m surprised they didn’t score more runs with the people they had out there,” Buck Showalter said. “It was a challenge. We were down four guys in the pen tonight, and we had to push some things.

“Less than four innings [from the starters] two days in a row has really put a tax on the bullpen.”

Relievers Jose Butto, called up from Triple-A Syracuse earlier in the day, and Grant Hartwig combined to cough up six runs for a 7-1 hole in the seventh inning.

Butto had recorded eight outs without allowing a run bridging the fourth and seventh innings, but he departed a 1-1 game with the bases loaded with two down in the seventh.

Hartwig, who entered with a 3.86 ERA over 17 relief appearances this season, walked the first batter he faced, pinch-hitter Jack Suwinski, on four pitches to snap the tie. He drilled the next batter, Jared Triolo, on the first pitch and another run scored on a passed ball by catcher Francisco Alvarez for a 4-1 Pirates lead.

The crowd cheered derisively after Hartwig finally threw a strike, but Jason Delay ripped a two-run double and Bryan Reynolds made it 7-1 with a triple past diving center fielder Tim Locastro before Hartwig departed to heavy boos.

“My timing was a little bit off. Obviously, it was a big situation, so you have to find it quick,” Hartwig said. “I didn’t do my job … I gotta attack the hitters in that situation, and ultimately have to be better.”

After Carlos Carrasco lasted only three innings Monday night, Showalter was hoping for some length out of Peterson. But the 27-year-old lefty was wild throughout his latest outing — walking six and hitting a batter — and departed a 1-1 game with two outs in the fourth.

“I was trying to make good pitches, instead of going with what we called, instead of committing to executing it,” Peterson said.

“He made enough pitches to keep us in the game, but to get deeper, that can’t happen,” Showalter said. “It’s something he’s gonna have to solve and we’re gonna have to solve together.”

Peterson (91 pitches) at least got the Pirates to strand seven runners over the first three innings, however. He struck out five, including strikeouts of Josh Palacios and Triolo with the bases loaded to escape the third.

“We’re gonna need him. He’s gonna get an opportunity,” Showalter said. “These guys at some point, they gotta run with it. He and Tylor [Megill], there’ll be some decisions that need to be made in the offseason and down the road that [GM] Billy [Eppler] and everybody will look at. It’s kind of in their corner, and they gotta run with it.”

The Pirates’ lone run against Peterson came on Liover Peguero’s home run in the second, negating a leadoff homer by Brandon Nimmo against Pirates starter Bailey Falter the previous inning. It was Nimmo’s second straight game going deep and the 10th time in his career that he led off a game with a homer for the Mets.

To lessen his defensive burden because of a recent upper-quad issue, Nimmo also made his fourth consecutive start in left field, his first appearances there since the 2021 season.

Still, Nimmo’s blast marked the lone run the Mets scored over 5 ¹/₃ innings against Falter, who entered with an 0-7 record and a 5.21 ERA this season.

The Mets recouped three runs on back-to-back homers by pinch-hitter D.J. Stewart and Jonathan Arauz against reliever Colin Selby in the seventh to close within 7-4.