"They're significant hamstring strains," New York general manager Zack Scott said Monday during a lengthy recounting of the Mets' aliments. "If I'm putting a time frame on that, we're probably looking at late June."
The team currently has a major league-high 16 players on the injured list, with right-hander Jordan Yamamoto set to join.
Three innings after rookie Johneshwy Fargas was hurt crashing into the center-field wall in Monday night's 3-2 loss to the visiting Colorado Rockies, Mets owner Steve Cohen tweeted: "Anybody want to suit up?''
Conforto and McNeil both got hurt on April 30.
Right-hander Carlos Carrasco, sidelined by a strained right hamstring, won't be ready to pitch for the Mets until late June or early July, Scott said. The six-week timetable from now is the same as the projection when Carrasco first got hurt on March 18.
When Carrasco was moved from the 10-day injured list to the 60-day IL on May 9, Scott said there had not been a setback.
"Probably when I spoke before, the word 'setback' to me implied something more specific," Scott said. "So it's kind of semantics a little bit. So obviously, when we're backing off, like I said back then, what we've done, that probably falls under setback in a different way."
New York was down to its fourth-string center fielder, following injuries to Brandon Nimmo (left index finger bone bruise), Albert Almora Jr. (bruised left shoulder) and Kevin Pillar (multiple facial fractures). Fargas was hurt on an unsuccessful attempt to catch a fourth-inning drive by Colorado's Garrett Hampson on Monday night and sprained the AC joint in his left shoulder. Fargas, playing his seventh big league game, finished the inning but then was replaced at the start of the fifth and sent for tests.
In addition, Yamamoto left Sunday's game at the Miami Marlins with soreness in his pitching shoulder. He was set to have an MRI on Monday, and he likely will go on the injured list on Tuesday, when ace Jacob deGrom is scheduled to be activated following right side tightness that has sidelined him since May 9.
New York's shortage of players reached the point Monday that James McCann, the Mets' starting catcher, made the initial start at first base of his 994-game professional career. Manager Luis Rojas said pitchers were told to get ready to play in the field if Monday's game reached extra innings.
"It's challenging, man. These things keep happening,'' Rojas said. "We react in the moment, saying, like, oh, not again.''
Third baseman J.D. Davis, out since May 1 with a sprained left hand, will likely play at least three more rehab games, including one at first base, before returning. Davis was 2-for-11 with one home run since starting at Triple-A Syracuse on May 18.
First baseman Pete Alonso, sidelined by a sprained right hand since May 18, was to swing with two hands on Monday, and he also will have at least one rehab appearance before returning, possibly next week.
Nimmo, out since May 2, has an injury that impacted a nerve.
"It's just something that's probably going to need some time, and we've got to figure out where we can get to a tolerance where he can play," Scott said.
Right-hander Noah Syndergaard, coming back from Tommy John surgery on March 26, 2020, is on track for a mid-June return after making his first minor league injury rehabilitation start. He pitched four scoreless innings for St. Lucie against Palm Beach on Wednesday.
Backup infielder Luis Guillorme, who hasn't played since April 25 due to a strained oblique muscle in his right side, could start a rehab assignment next week.
Right-hander Seth Lugo, working his way back from surgery to remove a bone spur from his pitching elbow, likely will be activated May 31, when he becomes eligible, or the following day. Lugo pitched a scoreless inning for St. Lucie on May 18 and allowed an unearned run in one inning for Syracuse on Friday.
The Associated Press contributed to this report.