Mets reliever Sean Manaea delivers a pitch during the second...

Mets reliever Sean Manaea delivers a pitch during the second inning of a game against the Seattle Mariners on Monday in Seattle. Credit: AP/Stephen Brashear

SEATTLE — This Mets team tends to do things the hard way.

It started in April, when their 12 straight losses put them in a dire early-season hole. It continued through the first two months, as they gritted their way through four western trips, this latest one taking them to Seattle and San Diego.

And it showed up again on Monday, when they embarked on their major league-leading 12th extra-inning game of the year, three more than any other team.

You know what else they’ll have to figure out how to do the hard way? Put together their longest winning streak of the season.

Cole Young’s 10th-inning, one-out RBI single off A.J. Minter keyed the Mariners to a 3-2 win at T-Mobile Park on Monday, snapping the Mets’ win streak at four — something they’ve accomplished twice this season but failed to build on. They’re now 7-5 in extra innings.

And though Sean Manaea turned in his best performance of the year, they still used an opener and six total pitchers, complicating an already thorny situation. The Mets intend to use Huascar Brazoban as an opener Tuesday, presumably ahead of Jonah Tong, meaning that the last thing they needed was “extra” anything.

“It’s not ideal,” manager Carlos Mendoza said. “It’s a combination of a lot of extra-inning games and then some of our starters not providing length. But it’s a part of it. You’ve got to keep going, you’ve got to find a way. I feel like we’ve been playing a lot of close games.”

The Mets’ offense, which bludgeoned the Marlins the night prior, was much quieter against a very good Mariners pitching staff — the only sparks (and only hits) being solo homers from Jared Young and Marcus Semien.

Semien’s homer, which came in the sixth, gave the Mets a 2-1 lead.

But though Manaea was dominant for five innings — he allowed one run and one hit with a walk and four strikeouts over five innings — his velocity was beginning to lag, and Mendoza made the call to the bullpen, summoning Brooks Raley.

That decision proved to be ill-fated: Josh Naylor nailed Raley’s hanging sweeper to hit a leadoff homer in the seventh, tying the game at 2.

“You’re looking at his longest outing of the year,” Mendoza said of the decision to pull Manaea. “He was already at the pitch count where he’s been, which is like low 60s, and you saw the velo drop. It was 89 mph] that last inning. You’re winning the game and you feel like you’re set up with your high-leverage guy. They’ve been pretty lock-down with Raley, Weave [Luke Weaver] and Devin [Williams]. It was just one pitch there.”

Manaea, whose fastball velocity had alarmingly been in the high 80s at the beginning of the season, maxed out at 93.8 mph Monday.

“I was just attacking guys,” Manaea said. “I was throwing everything for strikes. [I was] getting ahead . . . I just felt like it was a good pitching performance.”

His only mistake was to Colt Emerson with one out in the third: His 0-and-1 sweeper got just a touch too much of the plate and Emerson hit a 368-foot bomb to right to give the Mariners a 1-0 lead.

Young, though, tied it with a leadoff homer off Emerson Hancock in the fifth.

The big lefty has allowed two runs or fewer in his last four appearances as the “bulk” pitcher behind the opener. He had a 6.85 ERA through his first eight appearances and a 2.87 mark over his last four.

He wasn’t the only one showing signs of improvement, either. Semien again proved he was on that track with his go-ahead homer off Hancock, a 389-foot shot off a full-count fastball for his sixth home run of the year.

Semien is 6-for-13 in the last four games, with two homers, a double, four runs, four RBIs, two walks and three strikeouts. It’s an admittedly small sample size, his at-bats have also been looking progressively better, Mendoza noted.

But, of course, stealing this one from the Mariners wouldn’t be easy.

Naylor’s homer eventually sent the game to the 10th, with ghost runner Randy Arozarena stealing third as Minter struck out Patrick Wisdom for the first out. Cole Young then singled on the second pitch he saw, a cutter outside that he sliced the other way to left.

“You’ve got to give credit to the other team,” Jared Young said. “They executed tonight.”

As for all the “free” baseball, “It’s not ideal,” Young said. “But you want to come out of the other side of them. I mean, extra-inning games are great when you win them.”

Fun, maybe. Certainly not easy, though. But what about this team is?

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