Since taking over as manager of the Athletics in 2022, Mark Kotsay has seen 29 different players start a game at third base across five seasons. In 2026 Zack Gelof started 66 games at the hot corner, making him the player with the most starts at the position in a single season under Kotsay's watch, with Jace Peterson's 63 in 2023 and Vimael Machín's 62 in 2022 coming in second and third. 

With so many spots on the A's roster already being filled, from Tyler Soderstrom in left field and Brent Rooker at DH to Nick Kurtz at first, Shea Langeliers at catcher, Lawrence Butler in right, and Jacob Wilson at shortstop, there just aren't many spots that are open for players to break through on the offensive side of the ball. 

In his first three years with the club, Zack Gelof had been a second baseman, looking like a core piece of the roster in his rookie campaign in 2023, then struggling mightily in 2024 and suffering injury after injury in 2025. This season he was still chased by the injury bug, but in between those stints on the IL he looked more like the version we saw in '23. 

At the end-of-season press conference on Monday, Athletics Roundtable asked Kotsay what the plan is for him in 2027 — would he stay at third base, or would he be in the mix back at second?

"I played him specifically in September at third base," Kotsay said. "I believe that is a position that's been void for most of my tenure as manager here at the A's. We've tried to fill that third base position with a number of names... and no one has taken that position quite like Zack did. 

"I know he was a plus defensively at third base, because he told me," Kotsay joked. "He showed me his FanGraphs numbers. I love that about Zack. He knows exactly, you know, what his numbers are, what his deficiencies are, and he works at improving all of those deficiencies."

Gelof finished with a +9 defensive runs saved on FanGraphs, ranking him fifth among third basemen with at least 200 innings at the position behind Matt Chapman (+15), Alex Bregman (+15), Caleb Durbin (+13), and Maikel Garcia (+10). That was in just 572 ⅔ innings at third for Gelof. Over a full season, he'd be in the top three. 

Kotsay added that they talked about Gelof's value to the roster, and while he is viewed as a primary third baseman and will be preparing for 2027 with a large emphasis on the position, he will also take in some fly balls in the outfield during the offseason to continue to work on his versatility. 

Gelof finished the year batting .256 with a .322 OBP and a 114 wRC+ (100 is league average), adding a career-high 22 home runs and 16 stolen bases in 111 games played. 

He worked on his swing this past offseason, even while rehabbing his shoulder following surgery last September, and transformed his swing into the one that helped produce the numbers he put up this season. 

His goal when he got called up this year was to meet the ball level and lower his launch angle a little bit so that he was driving the ball consistently. 

He faced injuries in 2026 as well. Former A's third baseman Matt Chapman stepped on his hand, landing him on the IL for a couple of weeks. Less than a week later, he collided with a small fence in the side wall in left field in Detroit and missed nearly a month with a right knee laceration. Still, he kept picking up right where he left off. 

The other aspect of his development was on the mental side of the game. Last year he caught himself saying "they" when referring to his team and teammates, signaling that he didn't feel like part of the team as he recovered from an early-season injury.

"I was really proactive with it this off-season, making sure that I do the right things every day to stay on top of it," Gelof said of his mental approach this year after his two-homer game in the final series against the Astros. "It was really tough, especially losing some belief. Not necessarily in the organization, but just knowing that I'm good and I'm just gonna not necessarily show it, but work hard day in, day out, and know it's gonna work itself out.

"To start in Triple-A this year, coming off shoulder surgery, and to end up where I'm at right now, it feels really good. I just want to be a part of this team."