Alvarez out 8 weeks after thumb surgery

SAN FRANCISCO — The broad countdown to Francisco Alvarez’s return to the Mets lineup began Tuesday when the catcher underwent surgery to repair the torn ulnar collateral ligament in his left thumb.

Alvarez, according to the team, is expected to need an eightweek rehab — which would place his earliest return into late June. The second-year catcher stumbled rounding first base at Dodger Stadium on Friday and jammed the thumb. An MRI exam revealed the tear.

Alvarez initially said the timetable for return would be six to eight weeks, but it appears the Mets will play it conservatively with him.

“We’re looking at eight weeks because of the position he plays and it’s the left [thumb],” manager Carlos Mendoza said before the Mets’ 5-1 loss to the Giants at Oracle Park. “It’s one of those where we have got to be mindful and I know he’s going to try to push it, but we have got to make sure we get him back.”

Omar Narvaez (1-for-4) and Tomas Nido are handling the catching duties in Alvarez’s absence. Mendoza has said he intends to utilize both, but Narvaez as a lefthanded swinger could see most of the action.

Alvarez will be allowed to begin baseball activities once he regains 80 percent strength in the thumb. Mendoza wants to keep Alvarez around the team as much as possible so he feels as if he still belongs.

“So he doesn’t feel like he’s not contributing, whether it’s with meetings or the energy that he brings,” Mendoza said. “It’s one of those where we are going to have to talk to him every day to make sure he doesn’t push it too much.”

➤ Max Kranick was reinstated from the injured list and optioned to Triple-A Syracuse. The lefty, who pulled a hamstring during his first spring training start, will provide further rotation depth.

➤ Joey Wendle (0-for-4 with two strikeouts) started at second base and Jeff McNeil (2-for-4) shifted to left field, giving the Mets an additional left-handed bat in the starting lineup with Harrison Bader on the bench against Logan Webb.