NEW YORK -- The Mets may have entered this week with the lowest rotation ERA in the Majors, but that hardly meant they lacked starting pitching concerns. Of particular note, sophomore left-hander David Peterson entered Monday’s play with a 9.88 ERA in his last four starts, which prompted some around the team to call his job into question.

Problem is, the Mets don’t have an obvious in-house replacement, and the Trade Deadline is still nearly seven weeks away. Their best and easiest way out of that lurch is for Peterson to begin pitching the way he did as a rookie.

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That’s precisely what he did on Monday, holding the Cubs to a single hit over six innings in one of his most impactful starts of the season, a 5-2 Mets win at Citi Field. Peterson walked two, struck out three and eliminated a runner on a nifty pickoff move to second base, slicing his ERA from 6.32 to 5.60 in the process.

“We all love David, and he’s a bulldog out there,” left fielder Dominic Smith said. “We’re all going to go through a little bit of failure in this game. This game is a humbling game. I think the biggest thing is what do you do after that failure, and how do you challenge that? And I think he did a great job tonight against a first-place team.”

Peterson was not the only slumping Met to enjoy a renaissance on Monday, as Smith busted out of an 0-for-20 stretch at the plate with a walk, a single and a solo homer. But fewer doubts seemed to surround Smith, who posted MVP-caliber numbers a season ago. Although Peterson may also have thrived in 2020, his underlying statistics told the story of a pitcher at risk of regression. Specifically, his 4.52 FIP (Fielding Independent Pitching) and 4.39 xERA (Expected ERA) were both around a run higher than his 3.44 ERA.

Peterson quieted such thoughts early this season with a string of fine starts, relying on some improved velocity and a sharp slider to strike out 46 batters over his first 38 innings. But then came his recent malaise, which coincided with a decrease in slider effectiveness.

Following Peterson’s previous outing, in which the Orioles tagged him for four runs in 2 2/3 innings, manager Luis Rojas met with the left-hander, telling him to “simplify things … and think of the things that he can control” -- specifically his between-starts routine and in-game focus.

It was with all of that as a backdrop that Peterson took the mound against a Cubs offense ranking in the top third of the National League in both OPS and runs per game. Peterson did not do anything markedly different, but he featured better command of his signature slider. That, in turn, made his four-seamer more effective, resulting in five swings and misses on those two pitches. The fifth of those came on his final pitch of the night, a 3-2 slider that Peterson buried beneath the zone to Willson Contreras.

“If you’re struggling with something, you put a little more emphasis on it,” Peterson said of his slider. “Being able to work on all my pitches between starts has been good. I think it’s helped.”

And with that, the Mets -- at least for now -- have one less thing to worry about. Every strong start by Peterson and Joey Lucchesi brings the Mets closer to the Trade Deadline, closer to more reasonably priced opportunities to upgrade their rotation, and closer, eventually, to the returns of injured pitchers Noah Syndergaard and Carlos Carrasco. And if Peterson can string together more outings like Monday’s, he’ll be a part of the Mets’ plans regardless of who else is around.

Monday was a new beginning, nothing more. But it was one that Peterson sorely needed.

“The numbers on the surface don’t look very good, but he’s given us some really good starts,” said outfielder Kevin Pillar, who contributed a two-run double in the win. “I know he’s coming off a rough last few starts, but I think it just comes down to the culture and the environment that we believe in him. He knows that we believe in him. Luis believes in him. The pitching coach believes in him. This organization believes in him. And I feel like you reiterate that enough, it builds confidence in him.”