Zack Wheeler last pitched in a big league game in 2014. That season, he showed steady improvement until he got shut down, a product of innings limits intended to protect his arm. The next spring, he underwent Tommy John surgery.

But finally, after a bumpy rehab, Wheeler has returned to the big leagues. When he starts on Friday night against the Marlins, even the righthander himself isn’t sure exactly what to expect.

“Honestly, that was so long ago, I don’t even know if you can build on it,” Wheeler said recently.

For manager Terry Collins, the priority is remaining healthy, and that means watching Wheeler closely for signs of overthrowing.

“I think it will be taxing on him in both ways,” Collins said. “I think adrenaline wise certainly he’ll be amped up and emotionally I’m sure he’ll be nervous.”

Wheeler, 26, went 1-2 with a 5.11 ERA in four spring games, though his results improved as camp neared its end. He opened eyes with a fastball that touched 97 mph, the latest sign to team officials that he was finally healthy.

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Flores left in

Wilmer Flores will play a significant role against lefthanded pitching. But Collins is still working out just how he will be deployed.

Flores’ first start came Thursday night, when he played first base and batted cleanup against Braves southpaw Jaime Garcia. But while Flores is expected to remain in the lineup when the Mets face lefties on Friday night and Saturday night, it’s unclear how he’ll fit.

“There’s huge flexibility,” said Collins, who indicated he might also start Flores at third base or second base to get his bat into the lineup.

The righthanded hitting Flores batted .340 against lefthanders, with a .710 slugging percentage that was tops in the big leagues among those with at least 100 at-bats against southpaws.

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Said Collins: “He’s the guy right now when we face lefties, we’ve got to have him in there.”