The Oakland Athletics promoted Zack Gelof from Triple-A Las Vegas on Friday, rewarding a spring in which the infielder expanded his defensive repertoire to include the outfield. Gelof, who had spent the previous two seasons bouncing between the majors and minors, made his case by hitting .366 with four home runs in 11 games for the Aviators while playing second base and all three outfield positions.
Gelof debuted with the A’s in 2023, batting .267 with 14 homers in 69 games, but struggled in 2024 with a .211 average and a 188/38 strikeout-to-walk ratio. Injuries limited him to 77 games in 2025—30 with Oakland and 47 with Las Vegas. Determined to return, Gelof told manager Mark Kotsay during spring training that he was ready to play outfield, a position he had played only once professionally, in center field for Double-A Midland in 2022.
“I just wanted to open their eyes a bit, giving them as many options as they can have to put the best team on the field,” Gelof said before the call-up. “At the end of the day, I just want to help them win.”
Gelof’s late start to the season came after September surgery on his left shoulder. He played six spring training games before opening the year with Las Vegas (7-6). His improved plate discipline was evident: he walked nearly twice as often (13) as he struck out (7) with the Aviators.
The call-up came after Brent Rooker landed on the 10-day injured list with an oblique strain. Gelof joined the A’s in New York following their three-game sweep of the Mets. On Friday, he pinch-ran for Jeff McNeil in the ninth inning of a 4-0 win, scoring and finishing the game at second base.
“He’s a dynamic athlete,” Kotsay said Friday. “I’m hopeful that he can have as much success for us and for himself to really move the needle and solidify a spot here. … He’s earned this promotion.”
Gelof’s versatility traces back to his high school days at Cape Henlopen in Delaware, where he played football and soccer alongside baseball. Adjusting to the outfield required a different mindset, he said: in the infield, he must be alert on every pitch, while in the outfield he might go innings without a play. He called the transition “a lot of fun.”
Aviators manager Fran Riordan praised Gelof’s work ethic. “It looks like he’s played out there his whole career,” Riordan said. “It’s just who Zack is as a person. He’s never going to close his mind about doing anything and he’s always going to have the belief that no matter what he’s asked to do, he’s going to attack it.”
Thomas off to swinging start
Colby Thomas, another Aviators outfielder, is off to a strong start, leading the team with 13 RBIs and hitting .317. He opened the year with an eight-game hit streak. Riordan noted Thomas has improved his approach to become a more complete hitter. “He’s using the whole field,” Riordan said. “The one thing he’s really been focusing on is making more contact. When he makes more contact, he hits the ball really far.”
Road woes
The Aviators struggled in their first road trip, losing four games to the Sacramento River Cats, including two by a combined 20-0. A storm washed out Saturday and Sunday’s games, which were canceled since the teams won’t meet again until the second half. “It’s surprising — we haven’t played well in any phase of the game,” Riordan said. “If guys aren’t having success, they naturally tend to press and want to do more. We have to bring that back and get them back to being themselves.”
Up next
What: Aviators at Reno Aces
When: Tuesday-Saturday, 6:05 p.m.
Aviators starter: Tuesday — RHP Mason Barnett (1-0, 4.66 ERA)
