Theo Gillen#4

Montgomery Biscuits·BBRef

RSTeam La Llaga FLBTampa Bay Rays

Pos: Outfield

B/T: L / R

Born: Sep 12, 2005 (21)

Height: 6' 2"

Weight: 195 lbs

Owned: 0.6%

From: Chicago, IL

Drafted: 2024

Theo Gillen

Montgomery Biscuits BBRef

RSTeam La Llaga FLBTampa Bay Rays

Position: Outfield

Bats/Throws: L / R

Born: Sep 12, 2005 (21)

Height: 6' 2"

Weight: 195 lbs

Owned: 0.61%

From:

The Rays promoted Gillen from High-A Bowling Green to Double-A Montgomery on Sunday, Marc Topkin of the Tampa Bay Times reports.

Jun 22Rotowire

Gillen will move up to Double-A after slashing .342/.449/.589 with 12 home runs and 28 stolen bases over 265 plate appearances in 57 games with Bowling Green. The 20-year-old is considered to be one of Tampa Bay's top overall prospects, and he'll have a shot to climb to the Triple-A level before the end of 2026.

Gillen is hitting .333 with four home runs, three steals and a 22.6 percent strikeout rate in eight games for High-A Bowling Green.

Apr 13Rotowire

Gillen had an excellent first full season last year (151 wRC+ in 73 games at Single-A), save for the fact he didn't hit for much over-the-fence power (five home runs, .119 ISO). Less than 10 games into his first season at High-A and he's already one homer shy of tying his career high. Gillen leads the Sally league in ISO (.556) and wRC+ (251), but the Rays will likely keep him there for at least another couple months before challenging the 20-year-old center fielder with a bump to Double-A.

Gillen (undisclosed) played three innings in center field and drew an eight-pitch walk in his lone plate appearance in Sunday's 5-3 loss to Atlanta in Grapefruit League play.

Mar 2Rotowire

Gillen closed the 2025 campaign on Single-A Charleston's injured list due to an unspecified issue and has been limited to just 81 total games since being selected in the first round of the 2024 First-Year Player Draft, but the athletic outfielder reported to camp healthy and has drawn raves from the Rays' coaching staff. After Gillen impressed Sunday in his limited action in his spring debut, manager Kevin Cash told Marc Topkin of the Tampa Bay Times that he plans to have the 20-year-old play in a few more exhibitions prior to the end of camp. Gillen will likely head to Charleston or High-A Bowling Green for the start of the 2026 campaign.

Single-A Charleston placed Gillen on the 7-day injured list Aug. 16 due to an unspecified injury.

8/25/25Rotowire

A 19-year-old outfielder, Gillen has submitted an impressive debut campaign in full-season ball, slashing .267/.433/.387 with 36 stolen bases in 39 attempts and a 20.8 percent walk rate. The Rays haven't indicated whether Gillen has any chance of playing again in 2025, but he's likely done enough during his time at Charleston to earn a bump up to High-A Bowling Green next season.

Single-A Charleston activated Gillen (calf) from the 7-day injured list Sunday.

4/28/25Rotowire

The No. 18 overall pick in 2024, Gillen went 1-for-5 with a stolen base and a strikeout in his first game of the year for the RiverDogs. The 19-year-old center fielder has missed significant time due to injuries dating back to high school, but he was seen as one of the best prep hitters in last year's draft and has a chance to add notable power while stealing double-digit bases per season.

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