Out of all the potential issues the Mets could face, this wasn’t supposed to be one of them. Nolan McLean was their constant. Their ace who could stabilize, solve everything and stop losing streaks single-handedly during his starts.

In an ideal world for the Mets, Carlos Mendoza wouldn’t have needed to walk to the mound in the fourth inning Monday and pull McLean after just 78 pitches.

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He wouldn’t have needed to turn to his bullpen that early. But after delivering the worst start of his career last week, McLean one-upped that on Memorial Day, lasting just 3 ¹/₃ innings in his shortest outing with the Mets, surrendering seven runs on five hits, walking two and hitting two more batters in the Mets’ 7-2 loss to the Reds at Citi Field.

“It’s just bad pitching, honestly,” McLean said, turning a question about his stretch and windup splits into a telling line that he hasn’t needed to utter much throughout his young career. “If I’m just gonna be straight up, I just haven’t been pitching my best, and I gotta be better.”

The usual issues appeared again for the Mets (22-32). They couldn’t manage to score more than two runs for the fifth consecutive game and now have their second four-game losing skid of the season. They made Reds starter Nick Lodolo, who entered with a 7.20 ERA, look like an All-Star. The boos at Citi Field were temporarily replaced by “Let’s go Knicks” chants.

“I mean, they’re all frustrating,” manager Carlos Mendoza said when asked if this current stretch was more frustrating after the Mets appeared to turn a corner. “Especially when you’re not playing well. They’re all the same, to be honest with you. Yeah, it sucks.”

But around all that, McLean tossed what he called a second uncompetitive start in a row. The 24-year-old mostly breezed through opponents last season and at the start of 2026, too, and that’s exactly what happened Monday for his first 18 pitches.

McLean struck out the side in the first inning, but he quickly unraveled after hitting Reds third baseman Sal Stewart. He eventually loaded the bases and watched as Cincinnati scored its first two runs when Spencer Steer grounded into a fielder’s choice and McLean threw a wild pitch.

Then, JJ Bleday crushed a homer over the right-center field fence in the third, before Steer connected on a two-run single the following frame and Tyler Stephenson launched a two-run homer on the first pitch after a mound visit. McLean has allowed 16 runs, with 13 earned, across his last nine innings, walking four batters and hitting four others.

He has struggled to land his secondary pitches while also getting into bad counts, McLean and Mendoza agreed. McLean also admitted that he dealt with fatigue early Monday — perhaps trying to get “a little bit too much after it” to fix what went wrong after his start against the Nationals last week, he said. When he cruised through the opening frame, Mendoza thought, “Oh, he’s on today,” but everything unraveled from there.

And all it takes — with these Mets and this offense — is one bad inning to sink them, let alone three from their ace strung together. Marcus Semien homered in the sixth as part of a two-hit day to give a lineup missing Juan Soto (illness) for a second consecutive day a temporary jolt. Carson Benge added an RBI groundout the following frame to score Brett Baty.

But that was it. The Mets, as they’ve done all season, had other chances and failed to convert. They had runners on first and third with two outs in the third, but Mark Vientos rolled over a pitch and grounded out. They had the same situation again in the fifth inning, but this time, Vientos struck out on a curveball that hit him.

On most occasions, McLean could bail out the Mets. He could deliver a gem — or at least give them a chance to win. The last thing the Mets need is another rotation problem. Clay Holmes and Kodai Senga are already injured. Sean Manaea and David Peterson have already been demoted at different points, though Peterson is slowly working his way back. Freddy Peralta has mostly underwhelmed.

And now, at the very least, they have a worrying trend with McLean.

“He’s gonna get back on track,” Mendoza said. “He’s got too good of stuff for this to keep going. … It just sucks it happens on back-to-back outings, especially in the middle of this stretch.”