A's Seth Johnson Undergoes Knee Surgery

The Athletics announced this week that right-handed relief pitcher Seth Johnson has undergone surgery on his left knee with Dr. Tim McAdams at Stanford Orthopaedic Hospital, but Johnson is expected to be ready for Opening Day, per the team. As we wrote on Monday, Johnson is one of 12 players that will be out of options entering the 2027 season.

Johnson was acquired by the A's in the team's lone trade deadline move, with the green and gold sending outfielder Colby Thomas to the Philadelphia Phillies for the 28-year-old right-hander. 

Thomas did not appear for the Phillies at the big-league level, batting just .143 with a .207 OBP and a 9 wRC+ (100 is league average) with the Lehigh Valley IronPigs. 

Johnson held a 6.23 ERA (5.00 FIP) across 17 ⅓ innings with the A's. While the ERA was high, that can be partially explained by a .383 BABIP in a small sample of time with the club, in addition to his home run rate in Sacramento increasing from a 5.6% HR/FB rate in 16 ⅓ innings with the Phillies to a 17.4% HR/FB rate with the A's. 

His strikeout rate climbed slightly, up to 25.6%, while his walk rate dropped dramatically, going from 17.5% to 7.5%. A's manager Mark Kotsay said at the end of the season that limiting walks will be a huge focus for the club going into 2027 as they look to emulate a bit of how the Chicago Cubs were able to have success, even while giving up home runs at a high clip. 

When Johnson first arrived with the A's, he struggled as he tried to get his footing under him after a midseason trade. After a brief reset in Triple-A, Johnson was called back to Sacramento and held a 3.55 ERA across 12 ⅔ September innings. It was during this same time that his strikeout rate peaked at 26.9%, while his walk rate was a sterling 5.8%.

Johnson is a high-velocity arm that earned a 109 stuff+ grade this past season. If he has even league-average location, he could be an impact arm for a team looking everywhere for answers in the bullpen. 

Coming off surgery, Johnson will have to not only remain on the A's 40-man roster all offseason, but also make the club's 26-man roster out of camp due to that lack of options. The expected lockout could end up helping him out in both regards, as the roster freeze would keep his 40-man spot intact during the lockout, while any delay to the season would be added recovery time to ensure he's ready to go in 2027.