Rays Reportedly Set to Bump Top Prospect Theo Gillen Up to Next Level

The 20-year-old has a batting average over .400 so far in June

Apr 3, 2023; Washington, District of Columbia, USA; A general view of a Tampa Bay Rays hat and glove during the seventh inning of the game against the Washington Nationals at Nationals Park. Mandatory Credit: Scott Taetsch-Imagn Images | Scott Taetsch-Imagn Images

The Tampa Bay Rays have seen enough from the franchise's No. 1 prospect at High-A to reportedly move him one step closer to the ultimate goal of his minor league journey.

Outfielder Theo Gillen, MLB Pipeline's No. 40 overall prospect for 2026, has been called up to Double-A, according to the Tampa Bay Times' Marc Topkin and MLB.com's Adam Berry. This promotion has not yet been confirmed by the organization or its minor league affiliates. With the High-A Bowling Green Hot Rods and the Double-A Montgomery Biscuits both having off days on Monday, though, this move might not be officially announced until Tuesday, if it is finalized.

Gillen, the 18th-overall pick in the 2024 MLB draft, has been scorching hot so far in June, posting a .406 batting average and a 1.103 OPS in 17 High-A games. After spending all of 2025 at Single-A, the 20-year-old made his High-A debut at the start of 2026. And now, the young outfielder is seemingly ready to face a new challenge on his climb through the Rays' farm system.

Outlook on Rays' Theo Gillen in 2026 and beyond

Apr 6, 2026; St. Petersburg, Florida, USA; A general view of the stadium before a game between the Chicago Cubs and Tampa Bay Rays at Tropicana Field. Mandatory Credit: Nathan Ray Seebeck-Imagn Images | Nathan Ray Seebeck-Imagn Images

So far in 2026, Gillen has posted strong offensive numbers. He has a .342 batting average, a .449 on-base percentage, and a 1.038 OPS with 12 home runs, 44 RBIs, and 28 stolen bases in 57 High-A games this year. Last season, the lefty-swinging outfielder hit .267 with five homers, 18 RBIs, and 36 stolen bases in 73 Single-A games, so it seems like 2026 is on track to be his breakout campaign at the plate.

Gillen, who turns 21 in September, isn't expected to be a part of Tampa Bay's short-term plans at the big league level. But that could change depending on how the top prospect performs in his first taste of Double-A action following his reported promotion.

The Rays are currently 43-31 on the season and have the second-most wins in the American League. That could make them an interesting team to monitor at this year's trade deadline if they go all in on winning now. While Tampa Bay most likely wouldn't be extremely eager to trade its No. 1 prospect, the Rays reportedly discussed a blockbuster deal in 2023 that involved star third baseman Junior Caminero being sent to the Los Angeles Angels for Shohei Ohtani.

But, for now, many Rays fans will be curious to see if Gillen can replicate his success at the plate in High-A with the Double-A Montgomery Biscuits.