Unheralded Marlins Prospect Is Leading Arizona Fall League in This Category
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The Miami Marlins have tons of talented players coming up their pipeline.
Because of that, many can get lost in the shuffle when it comes to conversations about who is going to become franchise cornerstones for the big league club. And when it comes to pitching, it seems like it's going to be difficult to break through unless prospects are doing downright special things.
Fortunately for those on the outside looking in, they'll have opportunities to turn some heads. And for Jack Sellinger, he has gotten his opportunity in the Arizona Fall League and is making the most out of it by showcasing his elite curveball.
Jack Sellinger Has Highest Average Spin Rate on Breaking Balls Out of Every AFL Pitcher
Jim Callis of MLB.com took a look at the top Statcast performers after the Arizona Fall League reached its midway point. And thus far, nobody has thrown a curveball that has a higher spin rate on average than Sellinger, the Marlins prospect who is not ranked within their top 30
"Sellinger is the unquestioned spin master of the Fall League, as his curveball has produced the seven best individual spin rates (up to 3,521 rpm) and highest average (3,218 rpm). Hitters have gone 0-for-5 with four strikeouts against his bender, though they've teed off on his low-90s sinker and roughed him up for five runs in three innings," Callis wrote.
After being a 14th-round pick in the 2023 draft by Miami, the 25-year-old has shown well for himself throughout his time on the farm with a career ERA of 2.40 across 76 outings. During that span, he's thrown 112 2/3 innings. He's struck out 155 batters with only 61 walks issued, while holding opponents to a .176 batting average.
After striking out 89 batters in 66.2 minor league innings this year, Jack Sellinger (@MVScrappers '23) has punched out five over his first three @MLBazFallLeague innings.🏜️🌵
— MLB Draft League (@mlbdraftleague) October 27, 2025
The @Marlins 14th-round pick in 2023 reached Double-A this year for the first time, posting a 2.16 ERA… pic.twitter.com/8UxRTRMLwa
Sellinger reached Double-A for the first time this past season. He only made five outings at that level, but he gave up just two earned runs on four hits in 8 1/3 innings of work, striking out 11 batters while walking four.
The right-hander doesn't have the draft or prospect pedigree that suggests he's going to become a big time arm for the Marlins in The Show. But Callis gave two comparisons when it comes to the spin rate Sellinger has produced thus far in the AFL, and it's good company to keep.
"Dustin May (Red Sox) featured the highest average breaking ball spin rate in the Majors this year at 3,182 rpm with his sweeper, while Seth Lugo (Royals) reached the highest peak with a curveball at 3,557 rpm," he wrote.
Both of those players have either enjoyed successful careers or have flashed some immense upside. While Sellinger needs to continue performing at a high level the further up the pipeline ladder he climbs, doing what he's done in the Arizona Fall League thus far is a good sign.
