Rule 5 draft: Why Marlins will protect Joe Mack

Next Tuesday is the 2025 Rule 5 draft protection deadline. In my career covering the Miami Marlins, there has never been a more obvious candidate to be protected than Joe Mack.

That isn't to say that Mack's development journey has gone perfectly—if that were the case, he would already be in the major leagues. The 2021 MLB Draft pick was sidelined for the majority of the 2022 campaign due to hamstring injuries, then didn't hit a lick the following year despite being fully available (.218/.295/.287 slash line in 120 games at High-A). He briefly slipped off the Fish On First Top 30 prospects list during the 2023-24 offseason.

Some highly regarded amateurs never recover from that kind of early-career adversity. Just look at the players selected by the Fish with top-50 overall picks in the 2018, 2019 and 2020 drafts (Mack was the 31st overall pick in his class). As a prep prospect who signed for $2.5 million, Mack was most comparable to Dax Fulton and Nasim Nuñez, both of whom were true borderline cases entering their respective Rule 5 deadlines.

However, Mack sprung himself to prominence by the midpoint of the 2024 season. He hit 10 home runs during the month of June alone while being a 21-year-old at Double-A, and paired that power with MiLB Gold Glove Award-worthy defense behind the plate. It was apparent then that he had a rare skill set and exceptionally high floor.

Mack's breakout coincided with dramatic changes to the Marlins front office. Inheriting such a talented catcher did not deter new president of baseball operations Peter Bendix from acquiring more candidates to fill the position long term. Bendix added Agustín Ramírez at the 2024 trade deadline and Liam Hicks during last year's Rule 5 draft. As rookies in 2025, they combined to start 120 MLB games at catcher, producing well enough that Mack wasn't called up to Miami despite excelling against Triple-A competition.

But as the season progressed, Ramírez's receiving struggles and Hicks' limited power largely negated their redeeming qualities. Although both can meaningfully contribute to the Marlins in 2026 and beyond, neither of them profile as the primary catcher for a contending team. There is ample room for Mack in Miami.

As of this writing, the Marlins 40-man roster consists of 38 players, with Ramírez and Hicks being the only catchers (and there being serious doubt about Ramírez's future at the position). Even if the Marlins don't intend to carry Mack on their Opening Day active roster, every other team with open 40-man spots happily would as part of the Rule 5 requirements. Whenever a consensus Top 100 MLB prospect like Mack winds up in this situation, you need to protect the asset.

It is premature to anoint Mack as the Marlins' franchise catcher. Maybe severe injuries derail him, he fails to hit at the highest level or somebody else in the organization improves enough to surpass him on the depth chart. At least in those improbable scenarios, he could still be traded for talent that addresses other areas of the organization. That's preferable to a one-time $100,000 payment, which is all you get as compensation for losing a player in the major league phase of the Rule 5.

There is a sizable gap in value between Mack and the rest of the Marlins' Rule 5-eligible players. Keep an eye out for articles analyzing the others who are worth considering for 40-man selections—they'll all be housed in FOF's Fish on the Farm section.

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!