Noah Syndergaard of the Mets leaves a game against the Cardinals in...

Noah Syndergaard of the Mets leaves a game against the Cardinals in the seventh inning with head trainer Brian Chicklo at Citi Field on Saturday. Credit: Jim McIsaac

Even when the Mets win lately, they lose.

They beat the Cardinals, 8-7, on Saturday night, but Noah Syndergaard left in the seventh inning because of a strained right hamstring. Then the Mets’ best relievers — Robert Gsellman, Seth Lugo and Edwin Diaz — combined to turn a five-run game into one in which the potential tying run was thrown out at home plate for the final out.

“It’s hard right now,” manager Mickey Callaway said. “Even Lugo had to grind through his inning, which he did a great job of doing. It’s not easy for us right now, but tonight is a step in the right direction no matter how it happened.”

Syndergaard got hurt on the 102nd pitch of his night, a sinker to Jose Martinez for ball two. Callaway immediately visited the mound and didn’t hesitate to pull Syndergaard, who grabbed at the back of his right leg and walked with a limp to the dugout.

The Mets almost always downplay the severity of injuries initially. That they called Syndergaard’s issue a strain — and not “tightness” — suggests a certain degree of seriousness.

Callaway said he has “no idea” if Syndergaard will have to miss a start. Hamstring strains usually require at least a couple of weeks of recovery. Syndergaard declined to comment on his injury or his outing.

In a testament to his trust, or lack thereof, in the bullpen, Callaway had stuck with Syndergaard to open the seventh. Syndergaard, who had strep throat and was on antibiotics this week, needed 98 pitches to get through six innings. He also had a 10-minute mid-inning delay when plate umpire Brian O’Nora had to leave the game — O’Nora took a foul tip to the groin, started vomiting and did not return — and he sat through a long bottom of the sixth, when eight Mets batters led to two runs and a pitching change. “He was pitching pretty good and had 20 pitches left,” Callaway said.

Syndergaard’s final line was six innings and five runs (four earned). He struck out five.

The bullpen’s performance validated Callaway’s minimal trust. Gsellman allowed three runs (two of which were charged to Syndergaard). The Cardinals’ rally ended when Marcell Ozuna’s line drive to third base turned into a double play.

Lugo worked into and out of a bases-loaded jam in the eighth. Diaz, pitching for a third day in a row, allowed a run but got the save in the ninth. The would-be tying run, pitcher/pinch runner Jack Flaherty, was thrown out at home as he tried to score from first on a bloop to right that dropped between Michael Conforto and Jeff McNeil, who made a one-hop throw home to get Flaherty.

All that meant the Mets’ early highlight, another moonshot from Pete Alonso, was worth something. Alonso’s three-run homer — a 112-mph laser — shot into the first row of the third deck in leftfield before falling into the second deck. The distance: 458 feet, the longest Mets homer of the season.

Alonso said chief operating officer Jeff Wilpon recently razzed him for not having reached the third deck yet. Yoenis Cespedes has done it, Wilpon said. So has Albert Pujols. But not Alonso.

“I’m like, yeah? All right. OK. All right,” Alonso said with a smile. “There it is, Jeff.”

J.D. Davis had a career-high four hits (in five at-bats) and finished a homer shy of the cycle.

The Mets (34-36) remain in baseball purgatory as general manager Brodie Van Wagenen and his inner circle of decision-makers try to decide whether the team will be buyers or sellers as trade-deadline season approaches.

“Results matter. And at this point, we’ve played, I think, pretty well,” Van Wagenen said of his team, which hasn’t had a winning record since May 2. “We will continue to look for talent, we’ll continue to look for ways to improve, both in terms of what we have in that clubhouse now and what potentially exists outside of this clubhouse.”

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