The 31st overall pick in the 2021 Draft out of a New York high school, Mack signed for $2.5 million but batted just .217/.324/.303 in his first three pro seasons. He turned his career around in 2024 by deciding to hunt fastballs early in counts, which helped him total 45 homers in the past two years. He's also one of the better defensive catcher prospects in the game and led Jacksonville to International League and Triple-A National Championship titles in 2025.
Mack is somewhat of a one-dimensional hitter but as long as he's tapping into his plus raw power from the left side of the plate and providing quality defense, that's fine. He has an extremely aggressive approach as he looks to drive balls in the air to his pull side, and he chases a lot of pitches out of the zone. That mindset allows him to punish fastballs (1.074 OPS in 2025) but leaves him vulnerable to other types of offerings (.636 OPS).
A basketball and volleyball player in high school, Mack is more athletic than most catchers and can flash average speed once he gets going. Improved focus has helped him translate his soft hands into solid receiving and framing skills, and his agility help him block balls in the dirt. He has plus arm strength and a quick release, regularly recording sub-1.9-second pop times and throwing out 33 percent of basestealers last year.
Signed for an over-slot $2.5 million as the 31st overall pick in the 2021 Draft, Mack slashed just .217/.324/.303 in his first three pro seasons. He changed his approach in 2024, looking to attack fastballs early in counts, and doubled his previous career total by homering 24 times to rank fifth among Minor League catchers. He's also more athletic than most backstops and now looks like the future starter the Marlins hoped he would become.
Mack's quick left-handed swing and strength produce plus raw power that plays to all fields. He works deep counts and doesn't chase too often, but his approach got too passive at times in the past. He struggles to deal with breaking balls and changeups, so he has compensated by looking to do damage whenever he gets a fastball in the zone, and he did a better job of pulling and lifting pitches last year.
Also a basketball and volleyball player in high school, Mack is agile behind the plate and pounces on grounders in front of him. He has soft hands and has developed into a solid receiver and framer as he has gained experience and improved his focus. He has a plus arm and gets rid of throws quickly, which helped him erase 34 percent of base stealers last season.
One of the top catching prospects in the 2021 Draft, Mack went 31st overall and signed for an over-slot $2.5 million. He has struggled much more at the plate than expected, though the Marlins didn't do him any favors by sending him to High-A at age 20 last year after he missed much of 2022 with a hamstring injury. He batted just .218/.295/.287, with all six of his homers coming in the final seven weeks.
As an amateur, Mack looked equipped to hit for average and power with a quick left-handed swing, projectable strength and a disciplined approach. In his first three years as a pro, he was overly passive at times and hapless against non-fastballs. He still struggles with breaking ball but is compensating by doing a better job of attacking heaters in early counts while tapping into more power by turning on more pitches than ever.
There still are scouts who believe that Mack has to be better than he has shown in his first three years as a pro, and he has made strides with his defense. He's more athletic than most catchers and moves well behind the plate. He has improved his receiving and his focus and combats the running game with plus arm strength.
Mack ranked as one of the best catching prospects in the 2021 Draft after starring on the showcase circuit and leading Williamsville East HS (East Amherst) to the New York Section VI Class A championship in 2021. The Marlins selected him 31st overall that July -- five rounds earlier than his older brother, Charles, went to the Twins in 2018 -- and signed him away from a Clemson commitment for an over-slot $2.5 million. A severe hamstring injury cost him three months and left him at less than his best for much of his first full pro season, after which he made up for some of his lost at-bats as one of the youngest players (age 19) in the Arizona Fall League.
Mack showed the tools to hit for average and power as an amateur, but they haven't translated into production in pro ball. After he displayed the ability to work counts during a mediocre 2022 season in Single-A, his approach has deteriorated and his swing-and-miss issues have persisted in High-A this year. He still has a quick left-handed stroke and could grow into 20-homer power if he can make more contact and learn to lift more fly balls.
Mack also played basketball and volleyball as a prepster and is quicker and more athletic than most catchers. He has experimented with one-knee and traditional setups behind the plate, and he'll probably settle on the latter because he's more fluid with his receiving and throwing that way. He has the plus arm strength needed to deter the running game, but he needs to improve his focus when he's on defense.
Mack starred on the showcase circuit, establishing himself as one of the best catching prospects in the 2021 Draft, then led Williamsville East High (East Amherst) to the New York Section VI Class A title last spring. Three years after the Twins selected his older brother Charlie in the sixth round, he went 31st overall to the Marlins last July and signed for an over-slot $2.5 million. He scuffled offensively during his pro debut in Rookie ball, though he did draw 20 walks in 19 games.
Despite his early career struggles, Mack is equipped to hit for average and power. He slumped at the start of his high school senior season when he dropped his hands too low in his left-handed swing, but he corrected that flaw and displays a disciplined, gap-to-gap approach. His bat speed and projectable strength give him plus raw power and the potential to provide 20 or more homers on an annual basis.
Mack also played basketball and volleyball in high school and is quicker and more athletic than most catchers. He's agile behind the plate and has soft hands, though he'll need some time to polish his receiving. He features plus arm strength and records sub-1.9-second pop times on throws to second base.
Williamsville East High (East Amherst, N.Y.) featured the Mack brothers in 2018, with senior Charlie manning shortstop before going in the sixth round to the Twins and freshman Joe playing behind the plate. After repeatedly starring on the showcase circuit last summer, Joe emerged as one of the top catching prospects in the 2021 Draft. He led the Flames to the state Section VI Class A championship this spring, then went 31st overall to the Marlins and signed for an over-slot $2.5 million.
Mack is an advanced hitter with plus raw power. Though he slumped a bit at the start of his high school season when he dropped his hands too low at the plate, he has a sound left-handed swing as well as good plate discipline and a mature gap-to-gap approach. He makes repeated hard contact and has the bat speed and projectable strength to deliver 20 or more homers per season.
Though he's a below-average runner, Mack is quicker and athletic than most catchers. While he needs to polish his receiving, he has good instincts behind the plate and there's no question about him remaining there. He has a plus arm and repeatedly records sub-1.9-second pop times to second base.
In 2018, Charles Mack was a high school player outside of Buffalo, New York, who attracted a lot of attention from scouts and eventually signed an above-slot deal with the Twins as a sixth-rounder in that year's Draft. His brother, Joe, was a freshman on that team and even back then, scouts knew he'd be someone they'd be back to see three years later. After standing out at events like the East Coast Pro Showcase and Area Code Games both at the plate and behind it, he has the chance to best his brother in terms of when he gets drafted.
Mack has the chance to be an impact player on both sides of the ball. The left-handed hitter has the chance to be an above-average hitter, showing off an advanced approach all summer with an impressive ability to pick up base hits with two strikes. He has more alley-to-alley gap power, but he has the strength and bat speed that point to at least average power in the future. While speed isn't a part of his game, he's far from a clogger and runs well for a catcher.
All summer, Mack showed off plus pop times to second base, consistently under 1.9 seconds. He'll need to keep working on his overall defensive game, but given his baseball awareness, there's little question he'll be at least a solid average receiver, giving teams a complete package to consider signing away from his commitment to Clemson.
These run values are leveraged, meaning the base/out situation at the time of the event does impact the run value (thus introducing context outside the batter's own contribution).
Note: xHR tells how many of this player's batted balls would have been out of other stadiums. The "Adjusted" view here accounts for different wall heights, distances and environmental effects using Statcast Park Factor data.
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Year
HR
2026
6
7
7
7
7
7
8
7
5
6
5
7
7
7
8
7
6
6
7
8
6
9
8
7
6
6
3
3
9
9
9
Player
6
7
7
7
7
7
8
7
5
6
5
7
7
7
8
7
6
6
7
8
6
9
8
7
6
6
3
3
9
9
9
Note: xHR tells how many of this player's batted balls would have been out of other stadiums. The "Standard" view here accounts for different wall heights and distances but excludes environmental effects. It is based purely on the observed trajectory of the hit.
! Note: Shifts are through the 2022 season, Shaded starting from the 2023 season, Shift: three or more infielders are on the same side of second base, Shade: positioned outside of their typical responsible slices of the field. Learn more about how positioning is defined here
