Oakland A's 40-man Spring Breakout pool includes Top-100 trio, 31 non-roster invites

Leo de Vries is the headliner of Oakland’s preliminary 40-man Spring Breakout player pool, a condensed list the A’s published March 5 to spotlight prospects most likely to jump to Triple-A or the big leagues in 2026. De Vries enters camp as MLB Pipeline’s No. 4 prospect after Oakland acquired him from San Diego in the Mason Miller trade, a deal that sent Mason Miller and JP Sears to the Padres and brought De Vries plus Braden Nett, Henry Baez and Eduarniel Nuñez to Oakland.

De Vries’ 2025 season provides the reason for the spotlight: he made his Double-A debut at Midland at age 19 and, across 118 games between Midland and Single-A stops, hit .255 with an .806 OPS, 28 doubles, eight triples, 15 home runs, 74 RBI and 11 stolen bases. That combination of extra-base power and youth makes him the most obvious candidate from the A’s breakout pool to reach Triple-A quickly and to serve as near-term MLB depth.

Joining De Vries atop the non-roster invites are left-hander Jamie Arnold, ranked No. 41 on MLB Pipeline’s Top 100, and Gage Jump, ranked No. 57. Both Arnold and Jump are listed explicitly among the A’s Top-100 prospects invited to spring camp; the published excerpts do not include further statistical lines for either pitcher, leaving their exact assignments within the organization to be determined as camp unfolds.

Oakland’s announcement names 31 non-roster invitees to Spring Training, a group made up of 18 players who finished 2025 in the A’s organization plus 13 free agents signed to minor-league deals after the season. The list mixes prospect upside with experienced depth: left-handers Ben Bowden and Matt Krook, right-handers Geoff Hartlieb, Nick Hernandez, Brooks Kriske and Joel Kuhnel, catchers Bryan Lavastida, Brian Serven and Chad Wallach, outfielder Cade Marlowe and infielder Michael Stefanic are all among the non-roster invitees with big-league experience.

The A’s preliminary 40-man pool follows the standard Spring Breakout construction used across clubs: a 40-player preliminary roster that will be trimmed to a game-day group later in March. Leaguewide procedures show those 40-player pools are typically cut to 23-27 players on March 18, and teams build the prelim lists around their Top-30 Pipeline prospects while excluding injured players, Dominican Summer League-only players, and 40-man players who opt out.

Camp timing and national exposure matter for Oakland’s depth chart. The Spring Breakout schedule includes nationally televised matchups: the A’s and De Vries will face Brewers prospect Jesus Made on March 22 at 1:05 p.m. PT on MLB Network, and two days earlier, March 20 at 4:35 p.m. PT, Pirates prospect Konnor Griffin will square off with Tigers prospect Kevin McGonigle on MLB Network. Eight of the 16 Spring Breakout games will air live on MLB Network, with the remainder on team networks or MLB.TV.

One name that has circulated in some headlines, Henry Bolte, does not appear on Oakland’s published Spring Breakout roster. The A’s pool makes clear who the organization views as immediate depth for 2026: De Vries, Arnold and Jump headline a group that blends high-end youth with veteran non-roster arms, and the next two weeks of camp and the March cutdown will show which of those players are headed to Triple-A and which are on a faster track to the majors.