NEW YORK -- When Zack Wheeler approached home plate in the seventh inning Thursday, batting for himself with the bases loaded in a scoreless game, Mets manager Mickey Callaway envisioned grandeur.

“I was like, ‘He’s going to get a hit, and he’s going to throw two more innings, and he’s going to go into free agency [driving in] the only runs and throwing a shutout,’” Callaway said. “And that would have been great.”

Wheeler fulfilled the first part, but not the rest. His RBI single gave the Mets their first lead but, in what was possibly his final start as a Met, Wheeler served up consecutive home runs the next half-inning to fall in a 4-2 loss to the Marlins.

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As for his future, Wheeler offered little more than this nugget: “Whatever happens next, it is what it is.”

Wheeler’s public attitude toward free agency -- and the promise of a potential eight-figure payday -- has been one of nonchalance. Asked frequently the past few weeks about his final days in Flushing, Wheeler admitted only that it crosses his mind from time to time. That’s it. Thursday, he brushed aside insinuations that the end of an era was on his mind, deferring that sort of talk to a rapidly approaching offseason. But it is real now, whether Wheeler wants to acknowledge it or not.

“He deserves to go explore what can happen for him,” Callaway said.

Earlier Thursday, Wheeler seemed destined to fulfill Callaway’s hopes for him to “go into free agency on the highest note possible.” Showcasing his usual mid- to upper-90s velocity, Wheeler retired 20 of the first 21 Marlins he faced, striking out 10 of them to record his eighth career double-digit strikeout game. His RBI single off reliever Jarlin García provided a seventh-inning lead, which Brandon Nimmo extended with a sacrifice fly.

But Wheeler served up a leadoff double in the eighth inning, then a two-run, game-tying homer to rookie Tyler Heineman after a potential called strike three did not go his way. The next batter, Wheeler’s former teammate Curtis Granderson, hit a go-ahead shot to put him on the hook for a loss.

All told, Wheeler capped his season with a 3.96 ERA and 195 strikeouts in 195 1/3 innings -- exactly what the Mets hoped he would produce heading into the season. When the Mets declined to trade him prior to the July 31 Deadline, Wheeler went 4-2 with a 2.66 ERA over his final 11 outings.

“Unbelievable second half,” Callaway said.

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That the Mets ever employed Wheeler was a product of the negotiating stubbornness of former general manager Sandy Alderson, who acquired him from the Giants for the final two months of Carlos Beltran’s contract. At the time, Wheeler was 21, barely two years removed from going sixth overall in the 2009 Draft. Most scouts considered the trade a coup for the Mets; Wheeler immediately became the highest-ranked prospect in a farm system that already included Matt Harvey, Jacob deGrom and Steven Matz, and that would soon also gain Noah Syndergaard.

Those five pitchers never took a rotation turn together until last summer, however, in large part because of Wheeler’s litany of injuries. Tommy John surgery cost him the entire 2015 season. Rehab and complications from that operation kept him out all of ‘16, and additional arm trouble cut short his ‘17. It was not until the second half of last season that Wheeler found his groove, posting a 1.59 ERA over his final 10 starts.

As he enters free agency, Wheeler is now one of the most durable and polished arms available on the market. He has started 60 games the past two seasons, compiling more innings than all but 11 Major League pitchers over that stretch. One of those with more, Gerrit Cole, will headline this winter’s free-agent class. Barring a Stephen Strasburg opt-out, Wheeler may lead a list of cheaper alternatives that also includes Madison Bumgarner, Hyun-Jin Ryu, Jake Odorizzi, Dallas Keuchel and others.

When asked about those sorts of things, Wheeler speaks mostly about how he loves New York and loves the Mets, who “treated me fairly and very good.” Unspoken is the very real possibility that the Mets, with an escalating payroll, will not have the budget to compete with the masses of other teams that need starting pitching. So when Wheeler departs Citi Field on Sunday night, it could be for the last time as a Met -- a possibility that, at least publicly, he prefers not to discuss.

Asked about his curiosity regarding free agency, his future, his life going forward, Wheeler simply shrugged.

“I don’t know,” he said. “I guess time will tell.”