Tanner Houck To Undergo Tommy John Surgery

Red Sox starting pitcher Tanner Houck will undergo Tommy John surgery. Manager Alex Cora broke the bad news to reporters today, including Christopher Smith of MassLive. The right-hander has been on the injured list since mid-May with a flexor pronator strain, and he was recently transferred to the 60-day IL after the team pulled him off a rehab assignment. Even in a best-case scenario, he will not return to the Red Sox until late in the 2026 season, and possibly not until 2027.

Boston’s first pick (24th overall) in 2017, Houck pitched well for the Sox from 2020-22 (3.02 ERA, 3.50 SIERA in 146 IP). Yet, rotation battles and a bad back kept him from earning a full-time job in the starting five until 2023, and a terrifying liner to the face that summer kept him from pitching his first full season until 2024. It proved to be a year worth waiting for, however, as Houck made 30 starts with a 3.12 ERA and earned an All-Star selection that summer.

Houck came into the 2025 season as Boston’s number two starter, but he struggled badly over the first six weeks of the year. He pitched to an 8.04 ERA with a 15.8% strikeout rate and 8.4% walk rate through nine starts. Those numbers were heavily affected by two different outings in which he gave 11 earned runs and failed to escape the third inning. In fact, as MLBTR noted back in May, “If those two games were scratched from the register, his ERA would drop to 3.92, and his strikeout and walk rates would look much closer to what they were last season.” That said, to overlook two starts of such poor quality would be a mistake. Something was clearly wrong.

Houck began a rehab assignment in mid-June. While he wasn’t particularly sharp in his first three rehab outings, he looked much better in the latter two, tossing a total of 9 1/3 innings while giving up just one run on six hits and two walks. He struck out 10. In his outing against the Rochester Red Wings on July 9, he averaged close to 95 mph on his sinker, topping out at 96.8. Yet, he has not pitched since. He suffered a setback, either during that start or sometime shortly after, and the Red Sox officially returned him from his rehab assignment on July 19. MLB.com’s Ian Browne reported at the time that the issue was most likely “a recurrence of the right pronator strain” that landed him on the IL in the first place.

Earlier this week, Chris Cotillo of MassLive reported that Houck was seeking more opinions on his arm.  A couple of days later, the Red Sox transferred him to the 60-day IL, making room for trade acquisition Dustin May on the 40-man roster. Houck had already missed more than 60 days, so the move itself said nothing about his timeline, but chief baseball officer Craig Breslow seemed to imply the righty could be done for the season (per Cotillo). That is indeed the case, and now the question is if he will be able to return at all in 2026. The generally accepted timeline for a pitcher to return from UCL reconstruction is 12-18 months.

Breslow’s quiet trade deadline now looks even more disappointing. May adds depth to a pitching staff that has been severely hampered by injuries this year, but he’s not a high-upside arm. His days as a top-100 prospect are a ways behind him, and he has a 4.85 ERA and 4.30 SIERA in 19 games (18 starts) this year. He is also already well past his previous career-high in innings pitched. In other words, he’s not an arm the Red Sox can feel confident about starting in the playoffs (although they very well might have to). Until today, Red Sox fans could at least dream about Houck returning late in the season, pitching like he did in 2024, and taking the ball for game two of a postseason series. Now, however, that job will likely go to either Brayan Bello or Lucas Giolito, should the Red Sox hold onto their Wild Card spot.