MIAMI -- Rafael Montero's return to the big leagues wound up lasting all of one day.
That was not because of anything negative that Montero did on Tuesday, giving the Mets 5 2/3 innings of three-run ball in a 4-3 loss to the Marlins. It was simply due to the fact that with Montero unavailable for the next four days, the Mets wanted to option him to Triple-A Las Vegas in order to add another arm to the bullpen.
That turned out to be left-handed reliever Jack Leathersich, who will report to Miami on Wednesday for his first taste of the big leagues. Leathersich, 24, has showcased some much-improved command at Las Vegas, striking out 13 batters with two walks over seven appearances. He may not last on the roster for long, with the Mets employing a shorthanded bench and David Wright's return -- perhaps as soon as this weekend -- giving them an obvious opportunity to balance it. But the Mets believe Leathersich can be of use in the interim.
They thought the same of Montero, who also proved that he learned something at Vegas. Rather than attack the Marlins with only fastballs, as he did for much of his short-lived tenure as a reliever earlier this month, Montero relied more on the changeup and slider that helped him establish his value as a top prospect. Perfect through three innings, Montero did not run into serious trouble until Dee Gordon singled to lead off the sixth, moving to second on a fielding error and to third on a bunt.
At that point, the Mets had a choice: pitch to Giancarlo Stanton, arguably the National League's most-feared slugger, or give him first base in a scoreless game. The Mets chose to attack him, even after Montero threw three straight balls to open the at-bat. Battling back to run the count full, Montero left a 91-mph fastball over the plate, where Stanton redirected it into left field for an RBI single.
"I know he's real good," Mets manager Terry Collins said. "We wanted to go away on him and see if he'd chase. [Montero] threw too good of a pitch."
Overall, however, it was a positive step for Montero, whose conversion from reliever to starter initially opened the door for him to join the rotation and stick there. Dillon Gee's subsequent string of strong performances made that all but impossible, but the Mets have said they will periodically call up pitchers for spot starts to give Matt Harvey and others additional rest. Montero currently stands atop the list of candidates, saying after Tuesday's game that he plans to go back down to Vegas "as happy as always." Noah Syndergaard and Steven Matz will also be possibilities later this summer, depending on their Minor League performances.
Earlier in the day, the Mets optioned Danny Muno back to Las Vegas to make room for Montero. Muno, 26, recorded a hit in his first big league plate appearance, stealing a base later that inning. But he finished his first big league tour 1-for-6.