Mets minor-league catcher Francisco Alvarez at Clover Park in Port...

Mets minor-league catcher Francisco Alvarez at Clover Park in Port St. Lucie, Florida, on Feb. 18. Credit: Octavio Jones

Francisco Alvarez’s time has arrived. 

The Mets will call up their top prospect — and one of the top prospects in all of baseball — on Friday for the start of their series against Atlanta, sources said Thursday night, ending months of speculation about when or even if the 20-year-old catcher wunderkind would reach the majors this year. 

Alvarez’s role over the final six games of the regular season and perhaps in the playoffs “probably” will include at-bats as the designated hitter against lefthanded pitchers, according to a person familiar with the Mets’ plans. That would allow them to use his premier skill: hitting for power, especially against lefties.

Atlanta will start a lefty, Max Fried, in the series opener Friday. 

After a slow start upon being promoted to Triple-A Syracuse in early July, then missing about three weeks into September because of an ankle injury, Alvarez got hot at the plate, finishing with a .234 average, .382 OBP and .443 slugging percentage in 45 games at the top minor-league level. Syracuse’s season ended Wednesday. 

Those numbers were even better against lefthanders: .315/.424/.595. 

Hitting lefties has been a relative struggle for the major-league Mets, particularly at the designated-hitter position. Neither trade-deadline acquisition Darin Ruf nor Mark Vientos, another prospect, have demanded with their play more at-bats in those spots.  

Ruf is hitting .152 with a .197 slugging percentage with the Mets. Vientos is 4-for-28 (.143) with a .286 slugging percentage. 

Alvarez’s ankle injury — dubbed by the Mets as a “loose body” — seemed to contribute to his previous struggles. 

“I think he was dealing with the ankle for a while before he finally wanted to say something. So a good learning moment for everybody involved,” general manager Billy Eppler told Newsday last week. “It’s nice that there’s something material to point to [since] he wasn't putting up the numbers that he wanted or that some people were expecting. And frankly, I think jumping levels is hard to do." 

Alvarez spent the first half of this season with Double-A Binghamton, excelling in a league in which he was four years younger than the average hitter. 

He slashed .277/.368/.553 and earned rave reviews from the major-leaguers who made cameos with that club during rehab assignments, including ace Max Scherzer and catcher James McCann, who compared Alvarez’s batting-practice show to Pete Alonso’s. 

“There’s very few hitters that I watch in BP that I say, wow, that’s a real power tool. That’s what he’s got, a real power tool,” McCann said in June. 

Early this year, Alvarez reaching the majors this season looked like a long shot — to everyone but him, that is. In February, as the Mets’ pre-spring-training prospect camp began, during an interview that Alvarez himself initiated with a group of reporters, he declared his intentions for 2022: “Make it to the bigs. That’s the goal. This year.” 

On Aug. 4, two days after the trade deadline, at which the Mets did not bring in a new catcher, Eppler characterized a potential Alvarez promotion as a “never say never” situation. 

A primary concern for the Mets: They did not want to risk rushing Alvarez, especially because he plays the most defensively demanding position on the diamond. As advanced as his bat always has been, Alvarez’s abilities as a catcher are far more of a question mark. It isn’t clear whether he’ll be behind the plate at all with McCann and Tomas Nido already on the roster. 

Alvarez signed with the Mets — for a $2.7 million bonus — as a 16-year-old out of Venezuela in 2018.