NEW YORK -- As recently as a month ago, Pete Alonso chuckled when asked what he knew about Mets rookie Tylor Megill, eventually replying: “I knew he was a right-handed pitcher.” That’s no slight; for Alonso and many others around the team, there wasn’t much else to know. Megill, the organization’s 21st-ranked prospect, entered this season with all of one career start above Low-A ball. He didn’t seem likely to affect the team much this summer.

But shortly after Joey Lucchesi tore the UCL in his left elbow last month, necessitating season-ending surgery, the Mets -- lacking other, more tested options -- inserted Megill into their rotation. And now Alonso knows all about him.

Since joining the Mets, Megill has shown enough in three starts to establish himself firmly as a regular fifth-day option. He struck out seven over the first five innings of the Mets’ 4-2 win over the Brewers on Monday, allowing Alonso’s two-run double in the seventh inning to stand tall.

“How he’s handled himself, and how the game has given him an opportunity, and how he’s impacted our team -- it’s just been tremendous,” Alonso said. “What he’s been able to do, it’s awesome how he’s been so poised, calm, cool, collected, and just ready to rise to the occasion.”

With his parents in attendance, Megill cracked for his only run on Omar Narváez’s solo homer in the fourth inning, then he responded by retiring five of the final six batters he faced. The rookie right-hander finished with seven strikeouts to push his season total to 19. Only two Mets pitchers, Matt Harvey (23) and Steven Matz (20), struck out more over their first three career starts.

“He’s been super-clutch with how he’s carved guys up,” Alonso said.

While Megill’s fastball, which ran as hot as 97 mph, remains his showstopper, the most encouraging aspect of his night was almost certainly his changeup, which he threw 22 times for 16 strikes and seven swings-and-misses. Early this season, multiple scouts who saw Megill in the Minors called that changeup his defining pitch -- one that would make the difference between a future as a multi-inning reliever and a bona fide starting pitcher. Although Narváez’s homer came on a changeup, the rest of the Brewers struggled to make solid contact against it, frequently swinging over pitches that Megill buried beneath the zone.

It’s an offering that Megill has grown far more comfortable throwing over the past year and a half, following constant reps during games of catch and bullpen sessions.

“I’ve always had it, but now it seems like … it’s totally starting to flourish,” Megill said. “I’m able to command it now and throw it where I want to.”

Megill’s efforts on Monday earned him a third consecutive no-decision, which was no sure thing given opposing starter Brandon Woodruff’s early dominance. The Mets did manage to support their starter with a Brandon Nimmo double and a Dominic Smith sacrifice fly in the fourth, but Woodruff allowed nothing else until the seventh, when he put the first two runners on base on a Francisco Lindor walk and a Smith single. That brought up Alonso, who doubled down the line to give the Mets their first lead.

Once Edwin Díaz nailed down a somewhat shaky save, the Mets moved to 3-0 in Megill’s three starts. Tack on his 3.77 ERA and 19-6 strikeout-to-walk ratio, and Megill has done more than enough to remain in the rotation -- at least for the next few weeks.

He’s also given the Mets leverage heading into Trade Deadline season. Earlier Monday, general manager Zack Scott spoke of the likelihood that the Mets will add pitching with Carlos Carrasco, Noah Syndergaard and Lucchesi all still sidelined. As things stand, the Mets will almost certainly make a move (or three), but Megill has added another dimension to those discussions; thanks to him, Scott won’t be as desperate in negotiations as he otherwise might have been.

These days, Megill has become far more than just “a right-handed pitcher.” Manager Luis Rojas lauded two qualities in particular -- Megill’s poise, which has been a constant from his first day in the big leagues, and his adaptability.

“I think right out of the chute, facing two good teams, immediately he gets a big test to be part of this rotation like he is,” Rojas said. “He’s doing for us exactly what we needed -- probably more than what we needed. He’s been outstanding.”