BISCUITS UPDATE: Gillen's high ceiling has Rays excited for future
Theo Gillen is considered the top prospect in the Tampa Bay Rays minor league system. (Tim Gayle)
By TIM GAYLE
He’s the number one prospect in Tampa Bay’s minor league organization, but Theo Gillen doesn’t pay much attention to the accolades.
“I don’t spend too much time on my phone with social media,” Gillen said, “so I’m sure there are people out there that are excited about that but I’m just trying to take it day by day and go out and compete every night.”
Gillen, the 18th overall pick in 2024, played in Single-A Charleston in 2025 and started 2026 at High-A Bowling Green before getting promoted to the Biscuits the last week of June, where he faced the Biloxi Shuckers at DABOS Park.
“I’m super excited to be here, competing against these guys,” Gillen said. “I know they have a really good team, a really good staff, so I’ve just been taking it pitch by pitch and staying in the moment.”
A native of Austin, Texas, he played shortstop his entire career at Westlake High, batting .415 with seven home runs and 29 stolen bases his senior year when he caught the attention of Tampa Bay scouts, who wanted to convert him to the outfield.
“I was like, ‘I’m ready to go, let’s do it,’” Gillen said. “I worked out in all my pre-draft workouts infield and outfield, just so they knew I could do both. And here I am, playing in the outfield every day. It’s been a great transition.”
Earlier this month, Gillen was selected to participate in the annual MLB Futures Game, featuring the top prospects in the league. He was one of two selected from the Tampa Bay system.
While it’s been a seamless transition, Gillen admits there are moments when he misses the action at shortstop. During the offseason, he frequently works out with New York Mets infielder Brett Baty, a fellow Austin native.
“We take a lot of ground balls because he kind of plays everywhere,” Gillen said. “He’s the Mets’ glue guy out there. I miss being on the dirt, but you can’t be mad being in the lineup every night, going out there and catching balls to help your pitchers, helping the team win.”
He was originally committed to play college baseball in his hometown with the University of Texas, which recently made an appearance in the College World Series.
“I would have loved it,” Gillen said. “I just watched the guys in Omaha. Good to see them have a successful season. It would have been fun, but this is better. There’s nothing better than waking up every morning, thinking about baseball and getting ready to go to the clubhouse and get your body prepped.”
Gillen battled injuries in 2025 (and in high school in 2022 and 2023), but still has put together some impressive numbers. In 2025 at Charleston, he batted .267 with 12 doubles, five home runs and 26 stolen bases despite battling a calf injury in the first month of the season and a wrist injury in the final month.
In 2026 at Bowling Green, he batted .342 with 12 home runs, 12 doubles and 28 RBIs.
“He’s a guy that everyone is very aware of,” Biscuits manager Kevin Boles said. “We’re excited to have him. We’re going to move him to all three (outfield positions). We’re going to create some versatility with him, but center field is the priority right now, especially with (Austin) Overn out (with an injury). He and (Mac) Horvath are going to get the bulk of the playing time in center field.”
Gillen has an impressive Weighted Runs Created Plus rating, which measures a hitter’s total offensive value relative to the league average of 100. A rating of 130, for example, indicates that player is 30 percent better than the average. Gillen’s rating of 151 is among the top 10 in all of baseball for players aged 20 and under, but Boles is careful not to get caught up in the numbers.
“We’re not going to have those expectations of him,” Boles said, “because he’s new to the (Double A) level. He’s going to have to make some adjustments at this level. It doesn’t happen every day where you have a Chandler Simpson come in and take over. Usually, there’s a learning curve and I’m sure there will be some lessons learned here.”
Gillen is an eager learner, working daily to improve all aspects of his game.
“The Rays have all the data in the world we could ever look at,” he said. “It’s awesome to have that instant feedback. Offensively, it’s about managing the strike zone well and trying to do damage in the box. Defensively, having a good first step (and) route efficiency.
“Luckily, I have a great crew out there with (outfielders Noah) Myers, Horvath, (Ryan) Spikes, all those guys. So it’s an easy transition, especially when you have great counterparts when it comes to playing left, right and center. Managing the wall is a little bit different in every stadium but outside of that, it’s all about communication.”
Of the last 10 first-round draft picks signed by the Rays, six are currently playing Major League Baseball, while two others (Xavier Isaac and Brayden Taylor) are current teammates of Gillen. The newest member of the first-round draft club, however, said he doesn’t have any set goals or timetable for reaching the majors.
“I don’t set expectations on things I can’t control,” he said. “I’ve never been a big goal person. I just want to take every day like it’s a new challenge, with an open mind, and go out and compete in the games and see where that takes me. Learn as much as I can.”
The Biscuits open a six-game series on Tuesday against Birmingham. Tickets are available at biscuitsbaseball.com.