Just before Yoenis Cespedes was pulled from the game, trainer Ray Ramirez disappeared down the clubhouse steps with Terry Collins. Without context, this was a ghastly sight, even for Mets fans hardened by years of choking down the worst-case scenario.

Perhaps sensing this, the club quickly issued an announcement. After going 2-for-2 with an RBI double, the banged-up slugger was removed not because of another leg injury, but “because of the game situation.”

The situation was an eight-run deficit in what became a 14-3 thrashing by the Cubs, who used a sweltering night to treat Zack Wheeler like a birthday party piñata.

That Cespedes’ removal was more white flag than red flag qualified as the most encouraging development in an evening that unraveled when Wheeler recorded just five outs. When he made the slow walk off the mound for good, he had found a new low point in his big-league career.

“I just didn’t feel it tonight,” said Wheeler, who was at a loss to explain his uncharacteristic meltdown. “It’s unfortunate. I put us in a hole early.”

He lasted a career-low 1 2⁄3 innings and surrendered a career-high eight runs. Seven of them crossed the plate in the second inning, when Wheeler retired the first two he faced, then lost all semblance of his command.

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Rookie Ian Happ delivered the biggest blow, hammering the first grand slam of his career to give the Cubs a 6-1 lead. It came after Anthony Rizzo worked a bases-loaded walk, and after Cubs lefty Jon Lester singled.

For Wheeler, this was a clear sign of trouble. He hoped to throw a fastball away, but his command was so lacking that it sailed over the heart of the plate.

“I don’t know what it was,” he said. “I just didn’t feel right.”

Just like that, a beacon of consistency for a beleaguered rotation was reduced to throwing glorified batting practice. By the end of the second, the Cubs had chased Wheeler and sent 11 men to the plate. They’d finish the night with a season-high five home runs.

Until this gut punch, the Mets (29-35) had won four straight and five of their last six, a stretch in which Mets starters had allowed one run or none in every game. Wheeler began that run of dominance, allowing one run over seven innings Wednesday in Texas. The performance lowered his ERA to 2.41 in his last seven outings dating to April 29, making him one of the most effective starters in the majors during that span.

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Just one night after Jacob deGrom tossed the Mets’ first complete game of the season, Wheeler hoped to launch another stellar turn through the rotation. Instead, he experienced turbulence from the beginning.

“He’s going to have a bad one,” Collins said. “Tonight was it.”

The Cubs (32-32) haven’t looked like defending world champs partly because a powerful lineup has yet to get on track. Hoping to spark his bats, Joe Madden put Rizzo into the leadoff spot for the first time in his career. Two pitches into the game, the experiment proved worthwhile.

Wheeler fired a fastball and Rizzo hammered it into the blackened batter’s eye section in straightaway center. The blast buzzed the Home Run Apple and came to rest after an estimated flight of 462 feet. The worst was yet to come.

Lester allowed one run in seven innings, and later the Mets scrounged for any positives. A three-inning stint for Josh Smoker spared the bullpen further misery. In rightfield, Jay Bruce robbed a homer. In the ninth, Neil Walker and Lucas Duda hit solo shots.

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Fresh off the disabled list because of hamstring and quadriceps injuries, Cespedes departed Monday’s game early with a sore heel. Last night, Collins said he worried after Cesepdes was forced to stand around during a long second inning, which he called “one of the worst things to happen” for players dealing with tendinitis.

So Cespedes and his weary legs joined Wheeler, removed from a game that they’d rather forget.