SEATTLE — Just before Mike Zunino walked to the plate in the ninth inning, Edgar Martinez, a man who knows a little something about hitting, leaned over to Mariners manager Scott Servais.

“This is a good matchup,” Servais recalled Martinez, the team’s hitting coach, saying as the Mariners trailed the Twins by a run. “This guy throws a good sinker and that’s what Z hits.”

True enough, Zunino clubbed a two-out, two-run home run to give the Mariners a stunning 6-5 walkoff win Wednesday against the Twins. That was the shot that ignited the celebration at home plate: a flip of the helmet into the air, a dumped Gatorade jug, a giddy mob of jumping teammates.

The Mariners have won five straight games and nine of their last 10. At 30-30 this season, they’re back to .500 for just the second time this year and the first time since May 10.

“We’re playing good ball, and I think that’s the big thing: Playing up to your ability,” Servais said. “We certainly weren’t doing that earlier in the season.”

Zunino’s walkoff home run was as informative as it was dramatic. Just a month ago, the Mariners had demoted Zunino to the minors in the midst of a slump. They wanted to “get him right” and said all the right things at the time, but it was not the first time the Mariners’ young catcher had struggled so much at the big-league level that he required a trip to Tacoma.

In the ninth inning on Wednesday, with the Mariners down a run and two outs, right fielder Ben Gamel struck a single up the middle. That’s the hit that brought Zunino to the plate.

Zunino jumped ahead in the count, and then he jumped on his pitch: a sinker away that he crushed to right-center field, right back up the middle. That’s what had Servais and Zunino excited after the game, the part that shows his growth. Instead of trying to pull the pitch, as he might have in the past, Zunino did what he could with it and drove it up the middle. His natural strength did the rest.

“He hit a pitch I don’t think he would have hit in the beginning of the season,” Servais said. “The most exciting thing for me is the swing he took, he wasn’t trying to pull the ball out of he ballpark. He just put a good swing on it. He’s very strong, very gifted, a lot of power. He just has to make good contact.”

Zunino, who also homered in the third inning, agreed.

“That’s just something that comes from learning the swing, learning the pitch selection that you want to go to and ultimately trusting it,” Zunino said. “That’s sort of what the goal is in BP and the cage: I’m really trying to shoot that ROOT Sports sign in right-center in BP. To be able to get a pitch and do that in a game is a lot of fun.”

Since rejoining the Mariners, Zunino is hitting .302 with four home runs, four doubles and 14 RBI. He knows what he’s doing.

On Tuesday night, Zunino struck out three times. The next day, when Servais talked with him, he asked him about those at-bats.

“He knew right away what he was going to go: ‘I got a little quick, I gotta slow my leg kick down, my timing is going to be fine, I’m going to be OK,’ ” Servais said. “Just getting that response back vs. the wide-eyed ‘I don’t know’ — just a much, much different player right now.”

Mariners starter Yovani Gallardo pitched his best game in three or four weeks, Servais said, even though Gallardo allowed five runs. For most of the night he was able to avoid stress and damage, but in the fifth inning, he allowed four runs to score, all after he recorded two outs.

The big blow — the one that looked decisive until Zunino’s blast — was a three-run homer to Miguel Sano that gave the Twins a 5-2 lead.

But the Mariners kept inching closer. Tyler Smith drove in a run with a sacrifice fly in the fifth inning. Kyle Seager’s solo home run made it a one-run game.

And that set the stage for Zunino to come through in the ninth inning.