Kotsay's 'best friend' in the clubhouse: His son

June 14th, 2025
Mark Kotsay with his son Trey, right, and former big leaguer Chris Aguila at Aguila's training facility.
Mark Kotsay with his son Trey, right, and former big leaguer Chris Aguila at Aguila's training facility.

This story was excerpted from Martín Gallegos' Athletics Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

While the opportunity to continue life in baseball after a 17-year Major League playing career by managing the Athletics is one Mark Kotsay considers a dream job, the gig does not come without its drawbacks.

With a schedule that gets underway in February for Spring Training and can last into September or beyond, the grueling travel over those months leaves Kotsay with no choice but to sacrifice time away from his wife Jamie and three children, Grace, Sienna and Trey.

There are those rare occasions when Kotsay is able to bring his entire family along for road trips. Since taking over at the helm of the A’s in 2022, however, the presence of Kotsay’s son, Trey, by his side has become much more frequent.

“Our relationship has grown a lot,” Mark said. “Being around, [Trey] understands kind of the life and the ups and downs of the journey. It’s great to have him here, especially when you’re going through bad times, just to understand the value of the time itself and the impact it has on him.”

Trey, once a five-year-old boy who stood in a suite at then-AT&T Park in San Francisco and hugged his mom as he watched Mark take his final at-bat as a big leaguer, is now hoping to follow in the footsteps of his father. The 17-year-old infielder is a standout baseball player at Cathedral Catholic High School (San Diego) and recently committed to Princeton, where he plans to continue his playing career.

Trey’s emergence as a ballplayer recruited by a prestigious Ivy League school has coincided with his increased time around the A’s -- which is no coincidence to Mark. On any given game day -- when he’s not lending a helping hand to other A’s coaches or clubbies -- you will likely see Trey out on the field before games, taking ground balls alongside the likes of Jacob Wilson, Zack Gelof and Max Muncy.

“He’s worked really hard over the last few years,” Mark said. “I think part of that is being around this staff and the players and recognizing the work it takes to be able to play in the big leagues. To get anything in life, you have to put the work in. I think he’s recognized that and he’s done that.

“As a dad, I’m extremely proud of what he’s created for his future. Not all of that goes to me. It goes to his mom and his sisters, who, before him, have set the example as well.”

Kotsay relishes the memories he gets to create with Trey on the field together. Mark’s favorite moments, though, are those he can spend with his son away from the game.

“The support is invaluable,” Mark said. “You understand that doing this, you have this career that gives us an amazing opportunity in life. We’re blessed to have it. But at the same point, we lose valuable time with them that you can’t get back. But if you’re allowed to have it while you’re going through it and if you can figure out a way to balance that, when you look back on it, there’s always a trade-off. That isn’t really recognized while you’re going through it. It takes time when you get away from it to understand the impact."

It’s a relationship that goes beyond the typical father-son dynamic. Mark and Trey’s connection has evolved into something of a “best friends” type of bond in recent years.

“I can tell from recent weeks with him the impact that the ups and downs have on him as well,” Mark said. “He sees me going through it, and I think he’s starting to figure out ways to kind of bring joy into my life outside of the game. That’s the relationship growth we’ve been able to have over the last two years, and that’s been great.”

Mark is looking to soak in these opportunities for the next year or so. After that, Trey will be off to New Jersey for college. Education comes first, but Mark is also looking forward to watching his son flourish as a ballplayer.

“He’s grown so much,” Mark said. “I think he’s one of those kids who will develop later. He’s continuing to develop. The progress he’s made just in the last year has really elevated his ability to play the game at a higher level.”