NEW YORK -- Multiple times as he walked off the field on Tuesday night, Mets reliever Robert Gsellman had to stop, bend over and gather himself before continuing.

A day later, Gsellman learned why he was in so much pain: testing revealed a fractured rib, which will end his season. Mets manager Luis Rojas assumed Gsellman had suffered an oblique strain until he received a call from head trainer Brian Chicklo.

“I was actually really, really surprised, because it’s a rare injury,” Rojas said.

The team did not make Gsellman available to discuss his injury, and Rojas said he was unaware how exactly Gsellman cracked his rib while pitching. The Mets placed him on the injured list and recalled reliever Drew Smith from their alternate training site to replace him.

So ended a difficult season for Gsellman, who opened the year on the IL due to right triceps soreness. When Gsellman returned, he threw one strong inning on Aug. 8 before the Mets decided to turn him into a starter. That did not go as planned; Gsellman posted an 8.68 ERA in four starts, and was unable to stretch out because he was not making it deep enough into games. Once David Peterson and Michael Wacha returned from the IL, the Mets moved Gsellman back to the bullpen, where he allowed six runs on Tuesday in relief.

Gsellman threw a season-high 74 pitches in that outing, apparently injuring his rib on the final one.

“Last night, he was emotional,” Rojas said. “It was a tough season for him in those two ways, health-wise and then performing-wise. We just wish G to a prompt recovery, and he can come back healthy and strong, and come back and perform like we know he can.”

Rojas said he was unsure if the Mets would attempt to use Gsellman as a starter or a reliever next season. The 27-year-old made $1.2 million in arbitration this year, and could be due for a raise through that process over the winter.

“Right now, the plan is for him to get healthy and then we’ll go from there,” Rojas said.

Status unknown
The Mets have not issued an update about Jed Lowrie since Aug. 12, when they announced the infielder would receive a series of platelet-rich plasma and stem cell injections. At the time, the Mets said Lowrie’s timeline to return to the Mets would depend upon the outcome of his treatment.

But nearly a month later, Rojas said, “I don’t know what he’s doing.”

Managers generally receive daily updates on injured players performing baseball activities off-site. The fact that Lowrie is apparently not on that list with less than three weeks left in the season makes it exceedingly unlikely that he will play in 2020.

Lowrie, 36, has made just eight plate appearances since signing a two-year, $20 million contract in January 2019. He has spent the vast majority of his tenure on the IL due to left knee trouble and a right calf strain. Lowrie initially sustained a sprained left knee capsule in February 2019, before the team revealed that he was also battling more general, undefined “left side” issues.

In July, the Mets said Lowrie is suffering from PCL laxity -- a loose tendon in his left knee.

Honoring Clemente
Three Mets -- reliever Edwin Díaz, bullpen coach Ricky Bones and starting pitcher Seth Lugo -- wore No. 21 on Wednesday to honor late Hall of Famer and renowned philanthropist Roberto Clemente on his namesake day. Díaz and Bones are Puerto Rican natives who have been active in the community there. Lugo, who is one-quarter Puerto Rican, played for Team Puerto Rico during the 2017 World Baseball Classic.

“He was a tremendous inspiration for all of us in Puerto Rico,” Díaz said of Clemente, through an interpreter. “He did a lot on the field, but he did even more off the field. He was an idol for all of us in Puerto Rico, and we aspired to be just like him growing up.”

• Roberto Clemente Day

Díaz added that he would be in favor of MLB retiring No. 21 permanently, as the league did for Jackie Robinson’s No. 42.

“It would be a tremendous honor if they did retire the number 21,” Díaz said. “Obviously in the history of the game, there have been a lot of No. 21s in the game who have been really good, but I think he trumps them all.”