We know that Joe Mack will be protected by the Miami Marlins prior to Tuesday’s deadline for Rule 5 draft-eligible players. Nobody else in the organization should be considered a lock to receive the same treatment, but right-hander Josh White checks almost every box that a relief pitcher can.
A fifth-round pick out of UC Berkeley in 2022, White has gradually gotten better and better and better.
2022 minor league stats (Rookie ball/Low-A): 6.55 ERA and 14.0 K-BB% in 11.0 IP
2023 MiLB stats (Low-A/High-A): 3.46 ERA and 11.2 K-BB% in 65.0 IP
2024 MiLB stats (High-A/Double-A): 3.02 ERA and 21.9 K-BB% in 59.2 IP
2025 MiLB stats (Double-A/Triple-A): 1.86 ERA and 32.1 K-BB% in 67.2 IP
And those are only regular season stats—the Jacksonville Jumbo Shrimp won the Triple-A National Championship this year with the help of White’s three scoreless innings in the playoffs.
At various points during his professional career, White has struggled with his control and missing bats against left-handed opponents.
In 2025, however, there were no holes in his game, as illustrated by Prospect Savant. White worked himself into favorable counts, induced chases outside the strike zone at an elite rate and rarely got barreled even when allowing contact. The 24-year-old dominated in all situations and was remarkably consistent—he recorded strikeouts in 42 of 45 appearances, and even on his worst days, he never allowed more than two runs.
At 93.8 mph, White’s four-seam fastball velocity is a couple ticks below the average for MLB righty relievers. He compensates for that with an outlier, over-the-top arm angle that would be higher than any other Marlins pitcher.
About three-quarters of White’s strikeouts in 2025 came via his slider. Due to his release point and the difficulty that batters have distinguishing it from his fastball, it was an ideal putaway pitch. According to the Marlins’ propriety Stuff+ model, this slider was among the 20 best individual pitch types at any level of the organization.
The Rule 5 draft was made for guys just like White who have demonstrated that they can pile up whiffs in the upper minors. Over the past three years, 80% of all selections during the draft’s major league phase were pitchers, and most of them were deemed worthy of a pick despite being less effective and/or less durable than White. He has not been placed on the injured list since turning pro.
I do not want to inflate expectations for Fish On First’s No. 21 prospect. The correlation between MiLB reliever stats and MLB reliever stats isn’t particularly strong. Also, big leaguers equipped with the most advanced technology and most experienced scouts may be able to quickly adjust to White’s idiosyncrasies. He ought to get his feet wet in low-leverage situations and earn his manager’s trust from there, just like a typical first-time call-up.
But that’s getting ahead of ourselves. The decision facing the Marlins next week is simply whether or not Josh White merits a 40-man roster spot. On a team with two current 40-man openings and the likes of Zach Brzykcy and Josh Simpson taking up space, White absolutely belongs.