This Rising Prospect Gearing Up to Be Marlins' Biggest Sleeper in 2026
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The Miami Marlins have three key prospects who tend to soak up the most attention—Thomas White, Aiva Arquette and Owen Caissie. But with White and Arquette now out of commission for much of the spring, a few other prospects are going to have opportunities to shine.
White was sidelined recently with a Grade 1 oblique sprain, with an expected return date of late March or early April, while Arquette could potentially return in early April. Caissie is healthy and on his way to a successful season, but one other prospect could start gaining traction.
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Is Joe Mack the Marlins’ Biggest Sleeper?
So far this spring, 23-year-old Mack has been rising at the plate, slashing .333/.455/.667 with a 1.121 OPS and one homer through four games. During his 2025 campaign in the minors, he slashed .257/.338/.475 with a .813 OPS and 21 home runs through 112 games.
His numbers aren't as flashy as some of the other prospects across the Major Leagues, but there's something special here, and with more development, the franchise will be in good hands in years to come.
While he's on track right now, he will need to maintain this pace if he wants to be granted an opportunity in the Major Leagues. As skipper Clayton McCullough stated, per Louis Addeo-Weiss of Fish On First, "Joe Mack is going to play for us at some point. When that is, I don't know."
Regardless of the timeline set for Mack, he is undeniably becoming one of the ballclub's biggest sleeper prospects of the year. When Miami acquired Caissie in a trade package for Edward Cabrera, he immediately started headlining the Marlins' farm system.
But Mack was picked 31st overall by Miami in the 2021 MLB draft, and he's looking for an opportunity to break out. He comes in at No. 62 on MLB's Top 100 Prospects rankings, and he could find his way up that line if he continues to impress this spring and into the regular season.
The bar is already set incredibly high for the young catcher, but at this rate, he shouldn't have much trouble reaching it. Of course, it's only spring training, and things could always take a turn for the worse. However, he might not be an underrated player for very long. In true sleeper fashion, 2026 might just end up being a major year of success for him.
Maria Aldrich lives in the captivating Adirondack Mountains in New York where she can be found scaling cliffs, hiking in the High Peaks and paddling down local rivers. After graduating from SUNY Potsdam with a degree in Exercise Science and a minor in Wilderness Education, Maria began documenting her backcountry experiences through written stories. Over the years, she has found herself drawn to sports journalism and now focuses on MLB, WNBA, NCAA and NHL writing. She can be reached at mariaaldrich20@outlook.com.