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Colorado Rockies prospects: No. 16, Joe Rock

The 21-year-old lefty starter has an intriguing profile

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16. Joe Rock (267 points, 18 ballots)

Rock was the 68th overall pick of the 2021 draft and signed for a slot bonus of $953,100. The 6’6”, 200-pound, 21-year-old lefty starter earned that draft placement with a breakout 2020 summer performance in the All American Collegiate League, followed by a strong 2021 at Ohio University.

In 14 starts he threw 88 2⁄3 innings of 2.33 ERA ball with a 1.06 WHIP, 11.9 K/9 rate, and 2.7 BB/9 rate including a no-hitter in February. That 2021 season followed a lost 2020 in which, pandemic aside, Rock was declared academically ineligible. In 2019, Rock posted a 5.19 ERA with about as many walks as strikeouts, so there’s not a long track record of success.

After signing, Rock had four appearances in the Arizona Complex League. He threw eight innings, allowing two runs (one earned) on five hits and one walk with 11 strikeouts. That’s not much of a sample size, but it’s a strong beginning for Rock.

Here’s some video of Rock from late 2021 courtesy of FanGraphs:

In the January profile accompanying the above video, FanGraphs ranked Rock 22nd in the system as a 40 FV prospect:

Rock has an ideal pitcher’s build and an incredibly loose and fluid delivery for a guy his size. Coming off a redshirt 2020 at Ohio (he didn’t pitch at all before the shutdown), Rock had a huge uptick in performance — 117 K, 88.2 IP, 27 BB — and became famous after an early-season no-hitter. His frame, small school/cold weather pedigree and the missed year of reps are all late-bloomer traits that indicate his already solid stuff could become better with pro development. Rock’s fastball touches 96 mph, sits 91-94, and has tailing action that’s aided by his natural deception. It takes hitters a few looks at Rock from the batter’s box to really seem comfortable in there, especially the lefties. Flashes of an above-average slider and changeup occurred during instructs, though Rock’s finishing pitch has been his slider to this point. It’s imperative for Rock’s changeup to develop as it will help keep righty hitters off his fastball, which they get a nice long look at due to his arm slot. He has a leg up in this regard because of his mechanical fluidity and tailing fastball shape, which mimics that of his change. Even with a fully developed changeup, Rock’s fastball may end up playing best in shorter bursts rather than two and three times through a lineup, but at this moment he has a shot to pitch toward the back of a rotation.

Baseball Prospectus put Rock 10th in their November system write-up as a 50 OFP player:

Joe Rock was the Rockies second-round pick and added a little velocity after signing. Now the 6-foot-6 slinger still looks like he should throw harder than he does, but he was bumping 95 in the complex and pairs it with a potential plus slider. The delivery is repeatable enough for a tall, lanky southpaw, but the low-arm-slot will always leave reliever risk lurking in the profile. And yes, he’s likely a reliever, but he’s got a chance to start given the present strike-throwing ability and a chance to add more fastball velocity if he fills out his frame a bit more.

Rock was ranked #85 among 2021 draft prospects by and is currently 15th in the recent system ranking:

Already sitting in the low 90s consistently, there could be more velocity to come as Rock adds strength to his 6-foot-6 frame. He was up to 97 mph in his brief looks last summer and it plays up even more because he gets huge extension, so the ball gets on hitters in a hurry. His breaking ball is trending upwards as well, a pitch that’s somewhere between a power curve and a slider.

The Rockies knew coming in that Rock would have to work on his changeup since he didn’t need it much in college, but he has good feel for it and it could be a very effective third pitch once he trusts it. His lower slot provides funk and deception, making him very difficult to square up. He’s aggressive and loves going right after hitters, with the chance to do so in a big league rotation in the future.

Keith Law of the Athletic ranked Rock 12th in February:

Rock was 93-94 mph last spring for Ohio University, sporting an above-average changeup and fringy slider, with a funky delivery that adds deception but gives him timing issues, which can sometimes cause problems with breaking stuff.

Rock has an intriguing profile, boasting a projectable starter’s frame with a deceptive delivery. He’s shown improved velocity and feel for his change since signing, so Rock’s prospect arrow is up right now. That written, he doesn’t have much of a track record and like most starter prospects, Rock’s command and another secondary pitch will need to emerge to get high minors and MLB hitters out.

I’d like to see how Rock performs as a starter in affiliated ball in 2022, probably in Fresno or Spokane, before I place him near the system’s top 10. I ranked Rock 20th on my ballot with a 40+ FV tag because of the draft pedigree, stuff, and role weighed against the relief risk.