With the MLB offseason underway, the Red Sox finalized their 40-man roster Monday, designating right-hander Zack Kelly and left-hander Eduardo Rivera for assignment in the process.
Boston faced a 5 p.m. Monday deadline to reinstate players from the 60-day injured list to its 40-man roster. The Sox activated pitchers Justin Slaten, Johan Oviedo and Kutter Crawford, first baseman Triston Casas and outfielder Eli White.
Both Kelly and Rivera finished the season on the 60-day injured list, and the Red Sox still have an opportunity to trade either pitcher following their designations for assignment.
MassLive's Chris Cotillo previously reported that Rivera had drawn interest from other clubs, though he did not identify any potential suitors.
Kelly made his major league debut with Boston in 2022 and compiled a 4.04 ERA with 127 strikeouts over 131 1/3 innings in 115 appearances with the Red Sox.
The right-hander made a career-high 49 appearances in 2024 before earning a spot on Boston's postseason roster in 2025, following a strong September in which he posted a 2.84 ERA across 11 outings.
Kelly posted a 3.31 ERA in 17 major league appearances this season before being optioned to Triple-A Worcester in May to make room for Tyron Guerrero. He did not make Boston's Opening Day roster but joined the club a week into the season.
The right-hander landed on the injured list with right elbow inflammation in early July and did not pitch again.
Red Sox designated Zack Kelly for assignment, sources say.
— Chris Cotillo (@ChrisCotillo) November 2, 2026
Kelly was a logical candidate to be designated for assignment given his injury history and lack of remaining minor league options heading into 2027. He is also arbitration-eligible for the first time, with MLBTradeRumors projecting him to earn $800,000 next season.
Rivera, 23, made his major league debut this season after being called up to face the Yankees. The left-hander impressed in his first outing, tossing 3⅓ scoreless innings while allowing just one hit, walking none and striking out three.
He was optioned back to Triple-A Worcester before returning for his second appearance July 11 against the Mets. Rivera allowed one run over 3⅔ innings, walking two and striking out three.
His final two major league outings were less successful, as he surrendered seven earned runs on six hits and four walks before being sent back to the minors.
Red Sox announced the following move:
— Chris Henrique (@ChrisHenrique) November 3, 2026
Eduardo Rivera has also been DFA’d. pic.twitter.com/mnPGPzJXk0
Rivera's season took another turn in August when Worcester placed him on the 7-day injured list. Four days later, he was moved to the restricted list to attend to a personal matter. He was activated four days after that before eventually landing on the 60-day injured list with a lumbar strain.
Slaten was also reinstated after appearing in 36 games and posting a 4.60 ERA.
One of Boston's primary high-leverage relievers, the right-hander missed significant time with right elbow inflammation and was ultimately shut down in mid-September after additional imaging revealed "degenerative changes in his flexor mass."