Zack Gelof To Undergo Season-Ending Shoulder Surgery

SEPTEMBER 20, 4:12pm: Martin Gallegos of MLB.com writes that Gelof will head to Los Angeles to undergo shoulder surgery next week, and that he “should” have enough time this offseason to recover and return for Spring Training in 2026.

SEPTEMBER 20, 2:41pm: As expected, the A’s placed Gelof on the 10-day injured list today.  Left-hander Sean Newcomb was also placed on the 15-day IL due to left elbow inflammation, so Newcomb’s 2025 season will also come to an end.  To fill the two roster spots, the Athletics called up right-hander Scott McGough from Triple-A, and activated infielder Max Muncy from the 10-day IL.

Newcomb quietly posted a 2.73 ERA, 23.3% strikeout rate, and 7.9% walk rate over 92 1/3 combined innings with the Red Sox and Athletics in 2025.  He began the season in Boston’s rotation before being shifted into a long relief role, and the Sox then designated Newcomb for assignment in May and traded him to the A’s.  Assuming his elbow issue doesn’t lead to anything serious, Newcomb should be in line to land a guaranteed big league deal in free agency this winter.

SEPTEMBER 19: Athletics second baseman Zack Gelof suffered a dislocated left shoulder in tonight’s 4-3 win over the Pirates, manager Mark Kotsay told MLB.com’s Martin Gallegos and other reporters during the postgame media session.  Gelof hurt himself diving for a Bryan Reynolds grounder that ended up going for a deflected double, and had to be removed from the game immediately following the play.

The A’s will place Gelof on the 10-day injured list tomorrow, and needless to say, Gelof’s 2025 season is now officially over.  The dislocated shoulder is a rough ending to a season already marked by notable injuries for the 25-year-old infielder, as hamate bone surgery and then a stress reaction in his ribcage prevented Gelof from making his 2025 debut until July 4.

From there, Gelof had just two hits over his first 28 plate appearances before the A’s opted to send him back down to Triple-A.  Gelof was recalled in late August but hasn’t done much better, posting a .606 OPS over 71 PA between August 25 and September 18.  For the season as a whole, Gelof has a miserable 35 wRC+ from a .174/.230/.272 slash line and two home runs over 101 plate appearances.

This makes it back-to-back disappointing seasons for Gelof in the wake of his big 2023 rookie season.  That seeming breakout made it look like Gelof (a second-round pick in 2021) could be the Athletics’ second baseman of the future, but he followed up with an 82 wRC+ and a league-high 188 strikeouts over 547 PA during the 2024 campaign.

More will be known on the severity of Gelof’s dislocation in the coming days, and in a worst-case scenario, his availability for the start of Spring Training may be in jeopardy.  Even if healthy, Gelof cannot be viewed as a lock for an everyday job even in 2026, let alone over the long term.  With highly-touted shortstop prospect Leo De Vries now in the farm system, the Athletics’ future plans may now have De Vries at short and Jacob Wilson moving to second base, so Gelof will need to get healthy and re-emerge in 2026 to get himself back in the picture.