NEW YORK -- When the Yankees announced their 26-man roster for the American League Division Series on Tuesday morning ahead of Game 1 against the Guardians, the most surprising news wasn’t who made the team, but who had been left off.

Rookie reliever Scott Effross, who was expected to play a critical role in the Yankees’ depleted bullpen, was revealed to need season-ending Tommy John surgery on a torn UCL in his right elbow.

“It’s a huge loss,” said manager Aaron Boone. “[We] feel terrible for him. He’s kind of heartbroken over it. It’s a blow. I mean, Scotty came over here and pitched really well. I think he was going to have a really big role for us in our bullpen. But now we’ve just got to kind of support him and get him right.”

Effross was acquired by the Yankees in a trade with the Cubs on Aug. 1 in exchange for right-hander Hayden Wesneski, then New York’s No. 7 prospect according to MLB Pipeline. After pitching to a 2.66 ERA with 50 strikeouts in 47 games for Chicago and catching the Yanks’ eye in advance of the Trade Deadline, Effross compiled a 2.13 ERA in 13 outings (12 2/3 innings), including three saves, for New York.

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The 28-year-old righty had missed a month from late August to late September with a shoulder strain, but he returned in time for the final week-plus of the season. Effross’ last appearance came on Oct. 3 in Texas, where he pitched a scoreless ninth inning to earn that third save with closer Clay Holmes battling his own right shoulder strain.

Effross said on Tuesday that it was his previous outing against the Orioles that turned out to be the root of his elbow issue. After tossing a scoreless inning on Sept. 30, he started to feel “mild soreness” that he thought was typical for the end of the year, but as it continued to linger into a live batting practice session on Friday, he and the Yankees’ coaching staff decided that he needed a medical evaluation.

“No specific event triggered it. We thought we were staying on top of it, and it felt pretty good to keep throwing and go out there,” Effross said. “We decided to get it checked out, not thinking it would be as major as it was. But pictures came back and obviously we got the unfortunate news.”

Effross had an MRI taken on Saturday and the results came back the same day, simultaneously ruling him out for the ALDS roster and ending what would have been his first postseason before it had even begun.

“Obviously you know when you go in there, there’s the possibility of finding something you don’t want to see,” Effross said. “For me, I think it was kind of shocking. … [I’m] obviously very disappointed and frustrated, but it’s baseball. These things happen. Just kind of disappointed I won’t be able to go out there and help the team.”

The Yankees had envisioned using Effross in high-leverage situations against both right-handed and left-handed batters, alongside the likes of Holmes, righties Jonathan Loáisiga and Lou Trivino and lefty Wandy Peralta. Effross’ absence is the latest in a string of losses the Yanks’ bullpen has suffered in recent days and, really, throughout the second half of the season. It's all led to a reconfiguration that will see newcomers like Jameson Taillon join its ranks, at least for this series.

Effross and the Yankees are still going over the details for his upcoming surgery and ensuing recovery, but he said that he has already received a “really remarkable” level of support from his teammates, especially those in the clubhouse who have gone through the process before. That group includes Taillon, reliever Zack Britton and starter Luis Severino, among them.

In the meantime, Effross will watch as the Yankees start their journey toward what they hope will be a long postseason run, and he’s certain that the relief corps will respond to the challenge ahead.

Why? Because it’s all he’s known.

“Since I’ve been here, we’ve had a lot of shifting parts, a lot of moving parts, guys going down, guys coming back, and really, just everyone down there has been super resilient,” Effross said. “Everyone has taken the ball when they needed to do and done their job, and the starting pitching has been great.

“I’m expecting the same thing moving forward, and whoever gets the ball, I’m very confident in.”