Seth Johnson undergoes knee surgery but expected back for spring

Oakland Athletics right-hander Seth Johnson has undergone surgery on his left knee, according to MLB.com. Despite the procedure, the club expects him to be fully recovered in time for next year’s spring training, keeping him on track to compete for a bullpen role in 2027.

Johnson, 28, is a recent addition to the organization. The Athletics acquired him from the Philadelphia Phillies in a one-for-one deadline deal in early August, sending outfielder Colby Thomas the other way. The righty has drawn interest from multiple teams because of his power arsenal, even though the results in the majors have lagged behind the stuff.

Power arm with mixed major-league results

Johnson’s four-seam fastball averages close to 98 mph, and he also features a splitter, sinker, slider and curveball. Over 48 2/3 big-league innings, however, he has been tagged for a 6.84 ERA. His walk rate sits at 11.7%, a bit higher than ideal, while his strikeout rate of 24.7% hints at why clubs remain intrigued.

His body of work in the minors is more encouraging. After opening his career as a starter, he has worked exclusively in relief over the last two seasons. Since the start of 2025, Johnson has logged 95 innings at the Triple-A level with a 3.79 ERA. The walks are still elevated at 11.8%, but he has struck out 27.5% of the hitters he has faced in that span.

Busy transaction history and option crunch

Originally drafted by the Tampa Bay Rays in 2019, Johnson has already been part of several notable trades. He went to the Baltimore Orioles in 2022 in a three-team, five-player deal that featured Trey Mancini heading to the Houston Astros. Baltimore later shipped Johnson to the Phillies at the 2024 deadline in the trade that brought reliever Gregory Soto to the Orioles.

The Orioles added Johnson to their 40-man roster in November 2022 to shield him from the Rule 5 draft. He subsequently used minor-league options in 2023, 2024 and 2025, and the Phillies were granted a fourth option year for 2026. Going forward, he will be out of options, meaning any future move to the minors would require exposing him to waivers.

Opening in A’s bullpen, but little margin for error

That lack of options makes it harder for Johnson to hang onto a roster spot, but Oakland’s bullpen picture remains unsettled. With Mark Leiter Jr. heading into free agency, the projected relief group for next season is short on established veterans. Hogan Harris, Scott Blewett, Justin Sterner, Brady Basso and Chris Roycroft are all around 30, yet Harris is the only one with at least 115 major-league innings.

The Athletics could look to supplement that group over the winter, although the club has historically had difficulty luring free agents while playing in a hitter-friendly minor-league ballpark. That leaves a potential lane for Johnson to seize a role if he returns healthy and sharp in the spring. At the same time, his injury recovery, uneven MLB track record and lack of option flexibility leave him vulnerable if the A’s need to clear space on the 40-man roster.