SEATTLE — Some ace.

Here is what Masahiro Tanaka has aced this season when the Yankees run him out to the mound every five days: He has become the ace of surrendering home runs.

Tanaka surrendered four runs in the third inning, two on solo home runs to No. 9 hitter Mike Zunino and ex-Yankee Ben Gamel, greasing the skids for a terrible 6-5, 10-inning loss to the Mariners on Saturday night at Safeco Field.

The Yankees battled back all night, after Tanaka lost control of the game early.

Gamel was involved in the game-winner, too. He never really was given a chance by the Yankees, and he delighted in beating them. He led off the top of the 10th with a double off Adam Warren.

Then after an intentional walk to Robinson Cano, who broke a 4-4 tie on a first-pitch home run against his old Yankees teammate David Robertson in the eighth, Nelson Cruz lashed a walk-off single to left to score Gamel.

Tanaka has now surrendered a career-high 26 home runs this season. There is no doubt that young Luis Severino is the Yankees’ true ace and Tanaka is not even holding up his end of the bargain to be a No. 3 starter. He pitches much more like a fifth starter, a pitcher opponents know will crack at some point in the game.

That point came early — in that third inning.

Tanaka threw a mediocre fastball that Zunino hit out for his 14th home run, and then a weak curveball to Gamel for his sixth home run.

Afterward, manager Joe Girardi was left scratching his head about his supposed ace.

Tanaka now owns a 5.37 ERA. Brutal. Tanaka has allowed at least two home runs in eight of his 20 starts this season. Opposing hitters hit the jackpot against the right-hander.

“His stuff wasn’t very good,’’ Girardi began. “For whatever reason, that inning, his stuff kind of went away from him. Then he found it again. He had it, he lost it and then he found it.’’

Trouble is, by the time Tanaka finds his stuff, home runs have flown out of the ballpark and crooked numbers are put up on the scoreboard, the stuff of fifth starters.

“It was frustrating he couldn’t get out of that inning,’’ Girardi added. “He gave up the two home runs, got the second out, nobody was on and then he gave up two more runs and that’s the frustrating part.’’

So it’s home runs and much more, as Tanaka gave up three singles and hit a batter also in that third inning.

Perhaps the worst of this is that Tanaka never has any real answers to the questions that plague him. It is a similar refrain after his poor starts.

“I wasn’t executing pitchers, obviously that inning,’’ Tanaka said through an interpreter. “But I felt that throughout the game I really didn’t have my best stuff. I don’t think any of my pitches were sharp.’’

Therein lies the big problem. Tanaka just does not have the ability to dig deep and overcome his problems. He can’t find a way to limit the damage when things start to go south. There is just not a lot of grit there. He can’t stop the bleeding.

Aces find a way.

“After putting up some zeroes after that third inning is a positive I can take out of this game,’’ Tanaka said.

How about coming up with a positive to win a game and not have an ERA of 5.37.

As for all the home runs, Tanaka said, “It’s disappointing. It’s what it is and you’ve just got to keep on fighting.’’

That is all well and good, but it would be nice to start fighting. It would be nice to show a little more mental toughness and more of a winning will on the mound.

Along the way Aaron Judge’s MLB-leading 32nd home run was wasted as were two hits by fellow rookie Clint Frazier and a clutch, two-out, two-strike ninth-inning RBI single by Ronald Torreyes.

All gone to waste because the paid-like-an ace Tanaka cannot get the job done.