WASHINGTON — Robinson Cano rejoined the Mets on Tuesday after a short rehab assignment, but it’s clear the team intends to play it cautiously with the veteran second baseman in his return from a left hamstring tear.

“Whenever they want me in there, whatever it is, I’m just happy to be back,” Cano said before the Mets lost 11-10 to the Nationals.

Cano was on the bench and available to pinch hit, but did not play as Joe Panik remained in the lineup at second base.

According to manager Mickey Callaway, there isn’t a set plan on how the 36-year-old Cano will be used. Cano played just two rehab games at Single-A Brooklyn before returning to the big club. When he was placed on the IL on Aug. 5 he had been told the hamstring would need 6-12 weeks to heal.

“I don’t want to say I’m surprised, because I worked really hard,” Cano said.

J.D. Davis’ big Labor Day wasn’t enough to keep him in the Mets lineup, putting him on the bench with Amed Rosario as Callaway went with a left-handed look.

That meant Luis Guillorme (1-for-3 with a walk) at shortstop against Max Scherzer, with Todd Frazier (0-for-3 with a walk) at third base. Callaway indicated he toyed with the idea of using Jeff McNeil at third base, which would have allowed Davis to play left field, but ultimately valued the infield defense with Frazier.

Davis went 3-for-5 with two RBIs on Monday in leading the Mets to a 7-3 victory over the Nationals.

“You think about that, but Scherzer makes it a little bit easier and for obvious reasons,” Callaway said before the Mets’ loss. “There is such a big difference in righties and lefties with Scherzer and we wanted to get as many lefties in there and I was already thinking Rosie needed a day off so it made a lot of sense. We wanted Frazier there for his defense.”

Callaway said Dominic Smith’s workload has been limited in the first stages of his attempt to return from a stress reaction in his left foot. Smith, who has been on the injured list since July 27, is doing “weight bearing” activities, according to Callaway, and remains in New York.

The Mets named Bryn Alderson as their professional scouting director, replacing Jim D’Aloia, who was recently told his contract wouldn’t be renewed. Alderson, 38, the son of former Mets GM Sandy Alderson, had served as an assistant in the scouting department in recent seasons.

The team also named Jeff Lebow as assistant director, professional scouting. Lebow, 30, joined the Mets in 2011 as a baseball operations assistant.

The Syracuse Mets lost 14-13 to Scranton/Wilkes-Barre in a division tiebreaker to miss the International League playoffs. Jed Lowrie went 2-for-4 as the DH in the game. With the Triple-A schedule complete for the Mets, the organization will have to decide on a next step for Lowrie, who had been rehabbing with Syracuse.

Luis Avilan entered play 3-0 with a 0.50 ERA in his last 24 appearances dating to May 3. The lefty reliever had held left-handed hitters to 2-for-37 (.054).

Avilan faced one batter in the Mets’ disastrous ninth inning, giving up a single to Juan Soto. He was charged with one earned run in that nightmare frame.

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