HOUSTON -- Left-hander Colton Gordon, the Astros’ No. 11-ranked prospect by MLB Pipeline, was the lone prospect the club added to the 40-man roster ahead of Tuesday’s deadline to protect players from being exposed to the Rule 5 Draft. Houston has 39 players on its 40-man roster.

Gordon, who missed the spring and the first month of the season with a left lat strain, went 8-2 with a 3.94 ERA in 25 games (24 starts) over 123 1/3 innings at Triple-A Sugar Land, striking out 124 batters and allowing a .238 opponents’ batting average. Among qualified pitchers in the Pacific Coast League, Gordon posted the lowest opponents’ batting average and WHIP (1.22), while ranking third in ERA and fifth in strikeouts.

Players who were not added to the team’s 40-man roster by 3 p.m. CT on Tuesday are eligible to be selected by other teams in the Dec. 11 Rule 5 Draft at the Winter Meetings. The Astros have three players in their Top 30 Prospects rankings who will be eligible to be drafted: right-handers Alimber Santa (No. 16) and Rhett Kouba (No. 24) and outfielder Colin Barber (No. 30).

Another player the Astros didn’t protect was right-hander Alex Santos II, who was their top pick (supplemental second round) in the 2020 MLB Draft. He missed most of 2024 with right elbow problems, though he did rebound to lead the Arizona Fall League in strikeouts (26 in 17 2/3 innings) while displaying a mid-90s fastball, upper-80s cutter and low-80s slider.

Players first signed at age 18 or younger must be added to 40-man rosters within five seasons or they become eligible to be drafted by other organizations through the Rule 5 process. Players signed at 19 years or older have to be protected within four seasons. Clubs pay $100,000 to select a player in the Major League phase of the Rule 5 Draft. If that player doesn't stay on the 26-man roster for the full season, he must be offered back to his former team for $50,000.

Gordon will come to Spring Training and will compete for a spot in the back end of Houston’s rotation. The Astros took him in the eighth round of the 2021 MLB Draft out of Central Florida despite the lefty having Tommy John surgery that year. Gordon pitched for Team Israel in the 2023 World Baseball Classic.

In his three Minor League seasons, Gordon has a 3.74 ERA and has struck out 353 hitters in 305 1/3 innings.