Key Improvement to Know About Rockies Hot Pitching Prospect Jackson Cox

The right-hander went 4-6 with a 3.39 ERA in 23 starts for the Grizzlies, who made the playoffs and Cox was a key piece of the puzzle. He struck out 92 and walked 25 in 85 innings. He allowed batters to hit just .225 against him and he had a 1.12 WHIP. All of those numbers were huge improvements over what he did in 2023 at Fresno. But one number stood out.

Each week during the season, Baseball America (subscription required) published a hot sheet on prospects. Each article ends with a prospect they label as “helium,” as in a fast-rising prospect that may not be on anyone’s radar. Cox earned that designation back on Aug. 17 when he threw five shutout innings against Stockton that week, as he struck out seven hitters on 59 pitches.

But that’s not what Rockies fans need to know. The publication pointed out this improvement in Cox’s numbers from April to the end of the season:

“He allowed 12 earned runs in the season’s first month and just 20 the rest of the way. From May 1 on, he went 4-3, 2.31 with 84 strikeouts and 19 walks over 78 innings,” per the publication. In other words, he got better as the season went on.

Jackson Cox’s Professional Career Before 2025

Cox missed all of the 2024 season recovering after Tommy John surgery in 2023, which truncated his first professional season after he was drafted in the second round of the 2022 MLB draft out of Toutle Lake High School in Toutle, Wash.

In 2023, he started nine games and pitched in 10 with the Grizzlies, as he went 1-0 with a 7.26 ERA, with 32 strikeouts and 20 walks in 31 innings. Batters were hitting .307 against him and he had a 1.90 WHIP. He spent all of 2024 on the Grizzlies’ 60-day injured list. Once he was recovered, the Rockies opted to keep him at Fresno, in part because he hasn’t shown mastery of hitters at that level.

After 2025, he should be in line for, at minimum, a promotion to High-A Spokane to start the 2026 season.