No. 5 prospect Gillen not fazed by jump from high school to Minors

This story was excerpted from Adam Berry’s Rays Beat newsletter. To read the full newsletter, click here. And subscribe to get it regularly in your inbox.

HOUSTON -- This time a year ago, Theo Gillen had just graduated from Westlake High School in Austin. He was more than a month away from being selected 18th overall by the Rays in the 2024 Draft. He was used to playing two games a week, maybe three, in front of friends, family, classmates and scouts.

A lot has changed for Gillen over the last year, but he doesn’t seem to be fazed by any of it.

“It's so much more, going from two or three games a week to now, every night, you're getting ready to play in front of a good crowd,” Gillen said in a phone interview. “It's so much fun. It's new. Managing your body, making sure you're doing the right things, eating the right things -- that's definitely the hardest and the newest part.”

Gillen got a glimpse of professional baseball last year, playing eight games for Single-A Charleston. After being delayed by a calf injury this spring, the 19-year-old outfielder -- the Rays’ No. 5 prospect according to MLB Pipeline and No. 85 overall -- is off to an excellent start in his first full season for Charleston.

Just named the Carolina League Player of the Week, Gillen entered Thursday slashing .282/.436/.500 in 103 plate appearances over his first 23 games. He’s hit four homers, a triple and three doubles. Mostly batting atop the order, he’s scored 21 runs and driven in nine.

“He's been a true pro since being here. Getting a little taste of Charleston last year, of what full-season ball is and kind of taking a step forward this year, and the way he prepares and that kind of thing -- it really stands out for a young player to have that kind of mentality,” Charleston manager Sean Smedley said. “And then just his performance on the field, man, he can really do it all.”

That includes playing center field (and occasionally right) at what the Rays consider a high level despite being an infielder in high school. The club drafted him as an outfielder, believing his speed and instincts would play in center after shoulder surgery in high school affected his throwing arm.

Smedley said Gillen’s jumps and routes have continued to improve, and he’s taken well to the leadership role that comes with playing center. Gillen said he’s learned from his coaches and teammates, counting on them to help him with communication and positioning, and he’s committed to the RiverDogs’ daily pregame work to improve.

He’s also benefiting from his offseason training routine at home in Austin, where he said he focused on “being quicker” and “being elastic.” Team officials have seen that work pay off, noting Gillen’s greater athleticism and explosiveness in all aspects of his game. It’s even shown on the bases, as he has stolen 12 without being caught.

“It's definitely a different type of athleticism,” Smedley said. “Last year, it looked a little stiff, a little rigid. That comes with being young and kind of getting your feet wet, but this year, the athleticism has really taken off. It's fun to watch. He's moving like a center fielder.”

And his hitting has been pretty much as advertised, as he was regarded as the best high school hitter in last year’s Draft class. As impressive as any of his other surface-level numbers, considering his limited professional experience, is the fact that he’s recorded nearly as many walks (20) as strikeouts (25).

Smedley praised Gillen for his “really professional approach,” noting that he swings at pitches in the strike zone that he’s capable of driving without selling out for power or chasing much. It’s been an adjustment, Gillen admitted, because he’s facing better pitchers with nastier stuff than he saw in high school -- and he’s seeing them every night.

“Compete every pitch -- that's kind of my thing,” Gillen said. “Like, I could strike out five times in a row, but as long as I had competitive, quality at-bats all those at-bats, I'm walking back to the dugout satisfied and knowing that I put my best foot forward and competed.”

It’s a pretty mature mindset, especially for someone who was fresh off his high school graduation this time last year.

“You think back and you're like, 'God, I feel like it was just yesterday.' But at the same time, you feel like you've grown so much as a person since then,” he said. “You've learned so much about just managing yourself, living on your own, managing your body, professional baseball and everything. It's been a really fun journey, and I'm really excited to see what the future holds.”