Phillies opponents are trying to neutralize their lineup with left-handed pitching. It’s not working.

DETROIT — Even before they squared off with Detroit Tigers ace Tarik Skubal on Tuesday night, the Phillies faced more left-handed starting pitchers than any team in baseball.

Coincidence? Hardly.

Leadoff-hitting Kyle Schwarber and Bryce Harper represent the Phillies’ most feared power sources. Both bat left-handed. Meanwhile, righty-swinging Nick Castellanos has had a poor first half (89 OPS+ through Monday) despite a recent hot streak.

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In an attempt, then, to neutralize the second-highest scoring offense in the National League, many opponents believe left-handed starters have the best chance. It has been a concerted strategy. Entering the week, the Phillies led all teams with 1,238 plate appearances against lefty starters.

Has it worked? Not really. The Phillies ranked seventh in the majors with a .745 OPS against lefty starters and were 19-13 in games started by lefties, although the .594 winning percentage pales in comparison to their .717 mark against righties.

So, it’s no surprise that the Tigers will likely use an opener — lefty Tyler Holton, perhaps — to face Schwarber and Harper in the first inning Wednesday before turning to righty Keider Montero, who will be called up from triple A.

“I don’t really concern myself with whether it’s a right-hander or left-hander throwing,” manager Rob Thomson said. “Mainly because of the fact that Schwarber and Harper hit [lefties]. And [Bryson] Stott does, too, when he’s swinging the bat well. Our lefties for the most part do a pretty good job against them, so it doesn’t really concern me one way or the other.”

Fair enough. But Thomson does change the lineup based on the handedness of the opposing starter. Lefty-hitting Brandon Marsh usually sits against lefties in favor of light-hitting Cristian Pache in center field or struggling utilityman Whit Merrifield.

Marsh is batting .143/.225/.167 against lefties this season. Thomson continues to maintain that he doesn’t view Marsh as a platoon outfielder and that he wants to give him more at-bats against lefties. But those at-bats tend to come against lefty relievers when the Phillies have a lead.

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“When we’ve got the lead, I don’t want to get his defense out, so he’s going to have to take down a lefthander,” Thomson said. “It’s baby steps. Eventually, I think he’s going to be not a platoon. I think he’s going to get the bulk of left-handed pitching.”

Marsh got a hit Sunday against Diamondbacks lefty reliever Brandon Hughes. But when Thomson left him in Monday night to face Holton and fellow Tigers lefty Andrew Chafin, Marsh struck out and flew out.

“I just see a little bit of drift early against lefties,” Thomson said. “He’s got to stay in there. He’s got to take Schwarber’s approach, where you’re thinking left-center field or, depending on who the pitcher is, even straightaway left field just to keep him on the baseball as long as you can.”

The Phillies could pursue another right-handed hitter before the July 30 trade deadline to dissuade opponents from throwing as many lefties as possible. But other than the Atlanta Braves, with Max Fried and Chris Sale, most NL contenders aren’t loaded with lefty starters. The Dodgers, for instance, have only James Paxton.

“I think we’re fine,” Thomson said. “Our record is pretty good against lefties. It’s a little bit better against righties. But I feel good about it. The problem is, you don’t see [as] many lefties, so you’ve got to mix in Whit and Pache and [Edmundo Sosa] whenever you can.”

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Michael Mercado has been in the majors for two days. But when the phone rang in the bullpen Monday night, he figured it was for him.

“It was a big lead and they told me when I got called up, ‘Hey, be ready for Monday,’” Mercado said. “I was ready for it. I came in, and I was super-excited.”

Mercado threw a dirt-diving curveball to strike out Carson Kelly, the first batter he faced. He retired the next two hitters to complete a perfect major-league debut in front of his parents, who arrived in time from California.

“There’s no way to describe the feeling,” Mercado said. “Getting out on the mound is a feeling of accomplishment. It’s fantastic. Not that many people get to experience that. I’m super grateful.”

Mercado, acquired in an offseason trade with the Rays, impressed Thomson in spring training and was the Phillies’ best pitcher in triple A, posting a 1.71 ERA in 14 appearances. He got called up to be a low-leverage relief option after Spencer Turnbull returned to the rotation to fill in for Taijuan Walker, sidelined by a blister on his right index finger.

“I asked him, ‘Was he nervous?’ Because everybody is,” Thomson said. “He said, yeah, he was. But he said, ‘To tell you the truth, I was more nervous in the bullpen than I was on the mound.’ So, that’s a good sign.”

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The Phillies reinstated reliever Yunior Marté from the injured list and sent him to triple A. Marté, out since May 3 with right shoulder inflammation, gave up 13 hits and five walks in seven innings and posted a 7.71 ERA on his minor league assignment. He also has minor league options, unlike righty José Ruiz, who has pitched well since taking Marté’s spot in the bullpen. … Turnbull (3-0, 2.63 ERA) is scheduled to face his former team in the series finale.