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2021 MLB draft profile: RHP Kumar Rocker’s bumpy season puts him within reach

The Vanderbilt star was projected to be the first pick in the draft, but his up and down season knocked him down a few pegs.

Vanderbilt University vs University of Georgia Set Number: X163577 TK1

Early mock drafts are a useful exercise as a way for the reader to become familiar with the names in the top tier of a draft class, but no matter how certain it seems a year in advance the top spot never remains unchanged. For instance, that was the case with two college pitchers in the years Detroit selected first overall. Early favorite Emerson Hancock was dethroned by Spencer Torkelson in 2020, while Brady Singer was usurped by Casey Mize in 2018.

That trend held true this year as well. Vanderbilt pitcher Kumar Rocker entered the 2021 season with an astonishing amount of hype. If you take the articles written last summer or over the winter at face value, it was hard for many in the media to envision a world where he wasn’t the first player off the board. Nevertheless, now that draft day is just around the corner, it’s almost certain that Rocker will be available for the Tigers to draft third overall.


Among collegiate prospects in the 2021 MLB draft, none were more highly rated as high schoolers than Rocker. He was rated as a mid-first round talent in 2018 and the building blocks that would eventually make him a dominant force in college baseball were already evident. His most impressive pitch is a fastball that sits in the 93-96 miles per hour range and has the rising action that induces swings and misses at every level of professional baseball. He tops out at 98 mph, which is signifiant for a starting pitcher.

His other major weapon is a vicious slider that is already above major league average, according to FanGraphs scouting report, and has the potential for more. Despite not boasting much in the way of spin rate, the pitch routinely fools hitters into swinging outside the zone. He’ll also cross hitters up by dropping it into the outside part of the plate, eliciting awkward checked swings and called strikes.

Rocker also features two other pitches that have some projection, although they currently lag behind the others in terms of current utility. His changeup is a rare sighting, but FanGraphs and MLB Pipeline both assign it a usable future grade. He molded the low end of his breaking ball’s velocity range into a true curveball, a bender with plenty of vertical break. Evaluators were encouraged by its progress at season’s end and it will help keep hitters honest when he doesn’t have his best stuff.

An underrated aspect of Rocker’s game is the ease of his operation. On his best days, he pops mid-90s velocity without any more apparent effort than in warmup tosses. That kind of smooth delivery on high heat is a good sign – players with a big head whack or recoil are usually given poor command projections and a red flag for future injury.

2021 NCAA Division I Men’s Baseball Championship Photo by Jamie Schwaberow/NCAA Photos via Getty Images


There’s two versions of Rocker. The one we just described is the good version. The other, worse version came out to play too often this season, and it’s what has driven him largely out of consideration for the top pick.

There were stretches of the season when his fastball velocity cratered and sat in the 91 mph vicinity. During that time, his breaking stuff flattened out and he cracked up the effort in his delivery. He looked like a totally different prospect than the one that struck out 19 hitters in the NCAA tournament in 2019 or entered the 2021 season at the peak of his physical conditioning.

Despite turning the boat around and ending the season on a strong note, his rocky midseason stretch has some evaluators wondering which version of Rocker will show up in pro ball. Although his diminished form is still a draftable player, it’s disconcerting to think that a team may spend a top-10 pick on a low-velocity righty.

Rocker’s command is projectable due to his athletic ability and easy delivery, but it isn’t good enough to carry him to the major leagues on pitchability alone. That’s particularly the case if he winds up being forced to fight for his velocity, as it appeared he was during the worst part of his season. Heavy effort is a bad sign for command projection, which only compounds the issues he was having with his reduced stuff.

On the other hand, Rocker has carried a pretty serious workload in college. It’s not so unusual for a young pitcher to have a down stretch in terms of velocity. Teams will have a tough call deciding how much meaning to assign to that portion of his year.

Expected draft range: ¯\_(ツ)_/¯

Few people believe that the Rocker who was projected to be the top pick is gone for good. However, the level of confidence in his ability to get back to the prime version of himself varies from person to person, and thus, his draft stock is all over the place. Coupled with fairly high expectations in terms of a signing bonus, and Rocker has really become the wild card in the top ten picks.

There’s still a chance that he’s drafted first overall. It’s an outside shot, but among the top group of eight or so players, none has established himself as the alpha dog and the Pirates may decide they like Rocker’s pre-2021 track record and try to leverage a lower signing bonus. The Tigers were linked to him early on, and although that hasn’t been the case lately, a couple people who we’ve spoken to privately believe they could still interested in him if the top two picks don’t go the way Detroit’s front office expects.

Most mock drafts are unwilling to let him get past the eighth pick and send him to Kansas City if no one higher bites. When the rubber meets the road and draft day rolls around, though, there’s usually someone who drops well below pre-draft expectations, and Rocker seems like a prime candidate for that dubious title. MLB teams are notorious for being skittish at the top of the draft and there’s a decent chance that Rocker’s slump planted enough doubt in the league’s mind to let him fall to the middle of the first round.