Athletics Pitcher Seth Johnson Underwent Knee Surgery

The 28-year-old pitcher is expected to recover in time for 2027 spring training.

Updated on Oct. 5, 2026 in Baseball

Athletics Pitcher Seth Johnson Underwent Knee Surgery

Oakland Athletics pitcher Seth Johnson has undergone surgery on his left knee. The team expects the 28-year-old right-hander to complete his recovery in time for the start of 2027 spring training.

Why it matters

The surgery addresses a setback for the pitcher after he was acquired by Oakland in August 2026. Maintaining a healthy rotation is critical for the Athletics as they look ahead to the upcoming season.

Johnson has recorded a 6.84 ERA with a 24.7% strikeout rate over 48 2/3 major league innings. In Triple-A since 2025, he has maintained a 3.79 ERA and a 27.5% strikeout rate across 95 innings of work.

The players

Seth Johnson

He is a 28-year-old professional baseball pitcher who has played across several organizations including the Rays, Orioles, and Athletics.

Oakland Athletics

This is a professional Major League Baseball team based in Oakland that competes in the American League West division.

Philadelphia Phillies

This is a professional Major League Baseball team based in Philadelphia that competes in the National League East division.

Tampa Bay Rays

This is a professional Major League Baseball team based in St. Petersburg that competes in the American League East division.

Baltimore Orioles

This is a professional Major League Baseball team based in Baltimore that competes in the American League East division.

The details

The Athletics acquired Johnson from the Philadelphia Phillies in August 2026 as part of a trade involving Colby Thomas. Originally drafted by the Tampa Bay Rays in 2019, Johnson was later added to the Baltimore Orioles 40-man roster in 2022 to protect him from the Rule 5 draft.

2019: Seth Johnson was drafted by the Tampa Bay Rays.
November 2022: Johnson was added to Baltimore's 40-man roster.
August 2026: The Athletics acquired Johnson from the Phillies.
October 5, 2026: News regarding the surgery was published.
Spring 2027: Expected recovery for spring training.

Season Trajectory

This surgery forces the Athletics to adjust their pitching depth chart as they evaluate their roster needs for the 2027 season. The absence of a player acquired via mid-season trade impacts the team's ability to assess their full bullpen capacity during the winter months.

With Johnson sidelined, the Athletics front office faces increased pressure to identify alternative starting rotation depth during the off-season. His 11.2% walk rate in Triple-A suggests that his primary development goal upon return will be refining command to lower his major league walk rate.

The takeaway

Maintaining physical health is a significant hurdle for pitchers aiming to translate minor league success into consistent major league performance. Athletes often navigate complex medical recovery timelines while moving between organizations to solidify their spot in a big league rotation.