Blake Snell of the Tampa Bay Rays pitched well against...

Blake Snell of the Tampa Bay Rays pitched well against the Yankees on Saturday in his major-league debut. Credit: Jim McIsaac

Blake Snell, 23, is an excellent pitching prospect, and he looked even better Saturday in making his major-league debut against the Yankees. Just as the Rays figured he would.

But they didn’t need any advanced statistical analysis to tell them that. Snell throws lefthanded. Whatever else he was capable of doing would be a bonus. This season, when the Yankees are involved, that’s usually enough, and it almost was again.

If not for the Rays’ head-scratching charity, Brett Gardner never would have been in position to deliver Saturday’s 3-2 victory with his walk-off homer in the ninth inning. It was an important win, even for late April, and provided welcome joy during an otherwise bleak month.

As soon as Gardner connected against Erasmo Ramirez, he knew the ball was headed for the second deck, and he immediately pointed into the Yankees’ dugout in celebration. Before reaching the pinstriped scrum waiting for him at the plate, Gardner flipped his helmet. Didi Gregorius tossed dirt into the air, just as LeBron James does with his pregame chalk.

On this day, the Yankees could forget about the team’s most glaring weakness, which was painted over by a dramatic victory — the second time this season they’ve beaten the same team twice. And that Achilles’ heel has been lefthanded pitching, an April conundrum that will need to be solved, and very soon.

“If we want to be the last team standing at the end of October or early November, we’ve got to hit lefties,” Gardner said.

Snell became the first pitcher in the past century to debut against the Yankees and go at least five innings, strike out at least six and hold them to two or fewer hits, according to statistician Katie Sharp. He’s talented, but that’s an historically significant performance, and speaks to how badly the Yankees are scuffling against southpaws.

Before Gardner’s walk-off blast, the Yankees scored on a wild pitch in the first inning and tied it at 2 when Gardner pinballed a soft line drive off pitcher Xavier Cedeño’s glove with the bases full in the seventh. The reason they were loaded? A pair of four-pitch walks and Jacoby Ellsbury’s third catcher’s interference call this season.

The Yankees’ .609 OPS vs. lefties is second-to-last in the American League, barely above the Red Sox (.604). Can they reverse the trend?

“I think we will,” Joe Girardi said. “I’m starting to see good signs.”

We can take the manager’s word for it, or we can look at the results so far, which are dreadful. Chase Headley, who struck out twice against Snell, dropped to .095 (2-for-21) against lefthanders with six Ks. Alex Rodriguez is hitting .105 (2-for-19) against them, also striking out six times. And Aaron Hicks, acquired specifically to combat lefties, has been a patsy at .067 (1-for-15).

That hadn’t stopped Girardi from rotating Hicks into the lineup at the expense of either Gardner or Ellsbury. But with three more lefty starters on tap in the next four games — including Drew Smyly on Sunday and Cole Hamels on Monday night in Texas — Girardi won’t even have that option. Hicks is sidelined indefinitely because of “traumatic bursitis” in his left shoulder.

The Yankees have yet to make a roster move, but Hicks didn’t sound as if he’ll be ready to return in the next few days. His absence probably leaves Girardi to ride the Ellsbury-Gardner train in the meantime, and that’s not a bad thing. Gardner’s small sample size (4-for-13, double) against lefties has been positive and Ellsbury had one of the two hits off Snell.

Plus, with the Yankees’ stunning lack of power against lefthanded pitching, their best chance is with those two stirring things up on the basepaths. This season, the Yankees have only two homers against lefties: Carlos Beltran off Tony Sipp on April 6 and Brian McCann off Matt Moore in Friday night’s win.

“We haven’t played our best baseball,” McCann said. “But we’re a really good ballclub, top to bottom.”

That depends, of course, who’s facing them on the mound. The Rays made sure to line up their lefthanders for this trip to the Bronx, and it’s a strategy the Yankees are going to keep seeing as long as they continue to be vulnerable in this particular area.

“We’ll get a lot of practice at it,” Girardi said.

And they can’t get much worse.