Marlins Option Fulton, Kempner, White, De Los Santos, Serna to Triple-A Jacksonville

The Miami Marlins optioned five players to Triple-A Jacksonville on March 8, 2026, moving LHP Dax Fulton, RHP William Kempner, RHP Josh White, 3B Deyvison De Los Santos and SS Jared Serna to the Jumbo Shrimp. An internal report accompanying the transaction list added, "Two others reassigned to minors as roster shapes up," but did not name those additional players.

William Kempner’s option is the most detailed of the five moves on paper. MLB’s club notes show Kempner was assigned to the Marlins organization on February 28, 2025, worked his way from High-A Beloit to Double-A Pensacola and then to Triple-A Jacksonville during 2025, and had his contract selected on November 18, 2025. Kempner combined to go 7-3 with a 2.26 ERA, allowing 17 earned runs in 67.2 innings over 48 relief appearances across the three levels, and he totaled a career-high 95 strikeouts, the second-most among Marlins minor-league relievers behind RHP Josh White. MLB also records a 12.64 K/9 mark for Kempner, a 1.15 WHIP ranking fifth among Marlins relievers with at least 60 innings, and a strong playoff showing with Jacksonville, where he made two scoreless appearances (3 IP) and struck out six batters, including two hitless innings with three strikeouts in the Triple-A National Title.

MiLB’s March 8, 2026 transaction list confirms the five options and supplies position details: Deyvison De Los Santos is listed as 3B, Jared Serna as SS, Dax Fulton as LHP and Josh White as RHP, with William Kempner listed under his given name. Those entries appear alongside identical 03/08/26 date stamps for each player’s option to the Jacksonville Jumbo Shrimp.

The moves consolidate top organizational arms and position depth in Jacksonville. Kempner and Josh White, in particular, bring strikeout upside: MLB’s Kempner summary explicitly names White as the only Marlins minor-league reliever who out-struck Kempner in 2025. Deyvison De Los Santos and Jared Serna add infield depth at third and short respectively, while Fulton provides a left-handed option in the minors.

Sources supplied for these transactions do not identify the two unnamed players said to have been reassigned to the minors, and no quotes from Marlins front-office staff, coaches, or players were included in the provided material. The record shows a clear roster adjustment on March 8, 2026; what remains to be reported is whether those options were driven by 40-man roster moves, Opening Day protections, or specific big-league additions. For now, Jacksonville inherits five players with recent Triple-A and upper-minor track records, and Kempner’s 95-strikeout 2025 campaign stands out as the immediate bullpen story to monitor if Miami needs reinforcements during the season.