The Mets' Walker Lockett, right, reacts as the Cubs' Kyle...

The Mets' Walker Lockett, right, reacts as the Cubs' Kyle Schwarber celebrates scoring a run during the third inning on Thursday in Chicago. Credit: AP/Jim Young

CHICAGO — If you need convincing that the Mets’ pitching problems run far deeper than Dave Eiland and Chuck Hernandez, who were fired Thursday morning, consider what happened Thursday night.

The Mets lost to the Cubs, 7-4. They rolled out a series of hurlers more befitting a March exhibition in Port St. Lucie than a June contest at Wrigley Field: Walker Lockett, Brooks Pounders, Wilmer Font. By the time they were done, combining for six innings, the game may as well have been, too.

The Mets (35-40) are nine games back in the NL East. Five games below .500 matches their low point of the season.

“It feels like we’re clawing back, and then we take a step back,” Mickey Callaway said. “That’s how it feels. But we will never stop clawing back. That’s how we have to approach it.”

Lockett, a righthander called up from Triple-A Syracuse to make his Mets debut in place of Noah Syndergaard (strained right hamstring), allowed six runs in 2 1⁄3 innings.

He cruised through the first two, retiring all six batters and not allowing a batted ball to leave the infield, but fell apart in the third. Interim pitching coach Phil Regan made his first mound visit after Lockett walked Kyle Schwarber, putting two runners on with one out and one run already in. The end came quickly after that: Kris Bryant blooped a single to right, Anthony Rizzo scorched a double down the first-base line and Javier Baez lined a triple to deep center. In came Pounders, whose wild pitch allowed Baez to score, finishing Lockett’s line.

“The balls started getting up just a tad, a couple inches, and they barreled them up,” Callaway said. “It happened fast. I thought he was cruising and looking great until that point.”

Font tossed three scoreless innings. He struck out five, worked around three walks and one hit and lowered his ERA to 4.58. That effort positions him as a candidate to start when the Syndergaard/Lockett rotation spot comes up Tuesday in Philadelphia. In his past seven appearances, Font has allowed one run in 13 innings (0.69 ERA).

“He’s doing the job,” Callaway said. “I really like what I’m seeing.”

The Mets’ night was full of missed opportunities, especially early, including 0-for-5 with runners in scoring position. Robinson Cano, Carlos Gomez and J.D. Davis grounded into double plays — in the first four innings alone — to give the Mets an NL-leading 68 twin killings.

Pete Alonso’s laser of a two-run home run, which gave the Mets a 3-0 lead, was his 25th of the year. That’s one shy of the Mets’ rookie record of 26, done by Darryl Strawberry in 1983.

Todd Frazier homered in the ninth, the 200th of his career.

“It’s fun, it’s nice, it’s exciting,” he said. “It would mean more if we won the game.”

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