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

[Ely Sussman]

Two of the top talents that the Marlins acquired at the 2024 trade deadline are being protected from the upcoming MLB Rule 5 Draft, as is a pitching prospect who's coming back from Tommy John surgery.

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).

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[Slacker Mills]

The team should know what they have in Fulton at this point.  He should pretty much be in the best shape of his life.

[One Regend]

Least surprising outcome. The Marlins protected their best prospects, and they're going to need said prospects for their current rebuild.

At least two of the three prospects were considered must-keep. Jared Serna was just a bonus, honestly.

-You don't gamble with not protecting a potential cornerstone player who led the entirety of MiLB in Home Runs.
-You don't gamble with not protecting a guy with very high whiff rates and good run prevention metrics (FIP) that is fresh off of Tommy John who is ruled to be healthy in the entirety of 2024, ESPECIALLY not as a lefty.

Troy Johnston was really the only real loss here, and the Marlins made it pretty clear they don't want his services, after the Agustin Ramirez and Deyvision De Los Santos trades. If he somehow doesn't get selected in Rule 5, I expect him to be a MiLB Free Agent by the end of Spring.

Should've promoted him when you needed him, Marlins...

[Ely Sussman]

9 hours ago, One Regend said:

Troy Johnston was really the only real loss here, and the Marlins made it pretty clear they don't want his services, after the Agustin Ramirez and Deyvision De Los Santos trades. If he somehow doesn't get selected in Rule 5, I expect him to be a MiLB Free Agent by the end of Spring.

The question is whether they are leaving Johnston unprotected in the minor league phase. If that was the case last year, a team definitely would have snatched him.

I agree that they've made it clear they don't value him, so for everybody's sake, hopefully they handle it that way. Avoids the awkwardness of outright releasing him.

[rurrusuno]

I believe Deyvison De Los Santos will be the first one called up of those 3. He's ranked as our 4th best prospect and I'm sure we could utilize a power hitting corner infielder with potential mid-season, depending on where we are in the standings and of course if we have anyone on the injured list. 

I'm not yet sold on Jared Serna yet because he needs more AAA experience. Give him a full season there and then reassess in 2026. He does have speed and can play multiple positions but may be best suited at 2nd.

Dax Fulton definitely needs more time in the minors as well. He was out for the entire 2024 season and already has a past with Tommy John surgery. It would be nice to see him lower his ERA more in the minors this upcoming season. 

[Slacker Mills]

Troy Johnston is currently a better bat than De Los Santos (vastly better in DWL this year). I don't see De Los Santos making any kind of significant contribution in the majors - or Johnston for that matter. Maybe the Marlins could make him part of a trade package for a real difference-maker.