Marlins prospects Deyvison De Los Santos, Jared Serna, Dax Fulton selected to 40-man roster

The Miami Marlins have added 1B Deyvison De Los Santos, INF Jared Serna and LHP Dax Fulton to their 40-man roster. Ranked third, sixth and 15th, respectively, on the Fish On First Top 30 prospects list, each of them would have been eligible for the MLB Rule 5 Draft in December had they not been protected prior to Tuesday's deadline.

As explained by Fish On First's Kevin Barral last week, selecting De Los Santos (acquired from AZ for A.J. Puk) and Serna (acquired from NYY for Jazz Chisholm Jr.) were fairly obvious decisions. They both have exciting offensive potential and De Los Santos in particular is close to being major league-ready. It would be foolish for a rebuilding team to risk potentially losing them in the Rule 5.

Fulton was squarely on the bubble. The tall left-hander received a $2.4M signing bonus coming out of the 2020 MLB Draft. He has 12 games of Double-A experience (3.75 ERA and 82 K in 60.0 IP) and earned a non-roster invite to big league spring training in 2023, but he hasn't pitched in an official game since May 11, 2023 while rehabbing from Tommy John surgery (the second Tommy John of his career). He turned 23 years old last month.

Would another team have actually picked Fulton in the major league phase of the Rule 5 and stashed him on their active roster for the entire 2025 season? I guess we'll never know.

Entering Tuesday, Miami's 40-man roster was at 37, so no corresponding moves are needed to make room for De Los Santos, Serna and Fulton.

Notable Rule 5-eligible prospects who were not selected by the Marlins include 1B Troy Johnston (2023 Marlins Minor League Player of the Year), RHP Zach McCambley (third-round draft pick in 2020), INF Cody Morissette (second-round draft pick in 2021) and INF Jordan McCants (third-round draft pick in 2021).

Interested in learning more about the Miami Marlins' top prospects? Check out our comprehensive top prospects list that includes up-to-date stats, articles and videos about every prospect, scouting reports, and more!