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Colorado Rockies prospects: No. 21, Jackson Cox

The righty was the only high school player the Rockies drafted in 2022, but he was lost to Tommy John in July 2023

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21. Jackson Cox (148 points, 18 ballots)

Cox was Colorado’s second-round pick in 2022, 50th overall, out of a rural high school in Washington state — the only high school player the Rockies drafted in that class. To get Cox out of his commitment to Oregon, the Rockies signed the 6’2” righty starter for a $1.85 million bonus — well over the pick’s $1.54 million slot value. Cox’s calling card as a prospect is his 3,000+ RPM curveball, described as a slurve with “deep and late bite” which the 20-year-old pairs with a low- to mid-90s fastball and a developing change-up in a repeatable delivery. When healthy. Which he isn’t, because 2023 was mostly a disastrous year for higher-end Rockies pitching prospects.

Cox was assigned to Low-A Fresno in 2023 for his professional debut, where he was 2.9 years younger than league average. The Rockies handled Cox carefully, never allowing him to go past four innings in a start or 65 pitches an outing in his ten games (nine starts). Nonetheless, Cox suffered an injury that required Tommy John surgery in July (as did fellow PuRPs Jordy Vargas and Gabriel Hughes), which ended his 2023 season and might cause him to lose most or all of 2024 as well.

When he was on the mound, Cox had some growing pains with a 10.32 ERA in four May starts and an 8.53 ERA in four June starts. On a positive note, Cox’s final two starts in July were both scoreless, as he struck out 14 hitters in seven innings while allowing five hits and two walks. In all, Cox threw 31 innings with a 7.26 ERA (5.37 xFIP), 1.90 WHIP, 9.3 K/9 rate, and 5.8 BB/9 rate.

Here’s some video of Cox from a prospect showcase in 2022 courtesy of the Prospect Pipeline:

Cox was ranked 58th in his draft class by MLB.com and now slots in at 19th in the system as a 45 FV player thanks to a 60 grade curveball, 55 fastball, with 50 grades on the changeup and control:

One of the early things that stood out with Cox is his competitiveness on the mound, with a no-nonsense approach and a desire to attack hitters with what could be a very good three-pitch mix. He can get his fastball up to 95 mph with good running life, but it’s his curveball that has everyone buzzing. It’s a 1-to-7 breaking ball that registers elite-level spin rates and can be a real hammer out pitch with sharp bite to it. He has good feel for his changeup as well.

Cox has already added strength to his athletic frame since signing, which could lead to more consistent velocity once he’s back to full strength. He’s already shown an ability to command the ball to both sides of the plate and manipulate the spin and break on his curve, with some thinking he might eventually develop a distinct slider. His combination of pitchability and potential power stuff points to a future as a mid-rotation starter.

FanGraphs is less optimistic, rating Cox as a 35+ FV player and placing him 35th on Colorado’s list with a 60 grade on the curve:

If you’re looking for elite spin rates as part of a prospect’s foundation, this is your guy. Cox’s breaking ball routinely spins in the 2900-3100 rpm range and has huge two-plane wipe. His fastball, which will reach 96 mph but sits more 92-93, is relatively true due to Cox’s generic three-quarters arm slot and might get hit a ton in pro ball without mechanical alteration. A short-strider with a bit of cross-body action to his delivery, it may be as simple as tweaking Cox’s stride length or direction to alter the shape of his fastball, or parlaying his talent for spinning the ball into a breaking pitch that plays better with a sinker, but to this point neither happened. The track record of guys with curveball/sinker combos isn’t great, as those two pitches are typically easy for advanced hitters to parse out of hand. Cox is of medium build, not maxed out but not in possession of round-up physical projection that might make me think his fastball will play anyway. Cox is a fair prospect, just not the sort of teenage pitcher most teams (or this author) would give nearly $2 million of draft pool space to sign.

Keith Law of the Athletic ranked Cox 12th in the system before the 2023 season:

[Cox has] now stuff, with a plus curveball that shows very high spin, along with a clean delivery that keeps him online towards the plate, offering less projection than the typical 18-year-old but also not needing to gain stuff to potentially be a mid-rotation starter.

Baseball Prospectus ranked Cox 14th in Colorado’s org in November 2022:

Cox is a shorter, cold-weather second-round prep righty. There’s a lot of compounding risk in each subsequent adjective there, but his breaking ball was one of the better ones in the class, a high-spin hellion of a curve. He also sits mid-90s from a traditional three-quarters slot, but struggles to consistently throw strikes out of an uptempo, upright delivery.

With Cox, there are positives in the scouting comments, draft spot, and over-slot bonus that certainly make him worth ranking in this exercise. He’s got a foundational breaking ball to build around and mid-round starter potential. Then again, he’s a high school pitcher who is a long ways away from actualizing that potential into big league success, plus he’ll lose a year of development time after the surgery. I ranked Cox 27th on my list as a 40 FV player, which is probably about where he’ll slot until he’s able to return from his injury.