In last week’s early 2021 MLB draft rankings, Vanderbilt right-handers Jack Leiter and Kumar Rocker were second and third, respectively, on the list — and the top two pitching prospects on our board.
I had a chance to see the two pitch back-to-back in both ends of a doubleheader on Sunday in Nashville against Georgia State, so here’s a deep dive on both prospects and what could cause their stock to rise (or fall) heading into the 2021 MLB draft starting July 11 in Atlanta.
Kumar Rocker
Rocker was an elite prospect for years in high school, hitting the mid-90s as a sophomore and coming out of the gates in his showcase summer in contention to be selected in the top half of the first round. He was unique with his defensive lineman-like build (his father Tracy was an Outland Trophy-winning defensive tackle at Auburn, a third-round NFL draft pick, and is now the defensive line coach for the Eagles), but otherwise had the traits you’d expect in an elite, power-prep pitcher.
In his draft spring, he sat 93-97 and hit 98 mph while flashing a plus two-plane breaking ball, but how his build and command would age was still a long-term question. Accounts differ, but his bonus expectations seemed to be in the $4 million or more range (i.e., top ten pick money) though the teams with that kind of bonus pool weren’t quite convicted enough to pull the trigger on taking him out of high school.
This was in part because Rocker’s last prep outing was a playoff loss to fellow top pitching prospect Cole Wilcox’s prep team, when Rocker was on shorter-than-normal rest and worked 90-93 mph with 50- or 55-grade stuff and fringe command. This was a scary glimpse into what pro ball could look like for clubs wary of how Rocker’s command would play with lesser stuff and his effectiveness on shorter rest. It didn’t help that Wilcox hit 99 mph in this matchup on the same rest. Rocker then became famous down the stretch of his freshman year at Vanderbilt in 2019. He struck out 19 in a Super Regional no-hitter against Duke en route to helping Vandy win the national title in a College World Series where he won both of his starts and earned CWS Most Outstanding Player honors.
He was obviously executing at a high level in that stretch but was shakier in the brief 2020 season and early in 2021.
In my look, he sat 93-97 and hit 98 mph with his four-seam fastball, often used up in the zone with his best secondary pitch, that two-plane slider at 83-86 mph, often buried to his glove side low and off the plate to right-handed hitters. He has also added an 87-90 mph cutter, used mostly on his arm side, in place of his shelved changeup.
Rocker doesn’t get much swing-and-miss on his fastball, so he’s relying on his breaking pitches more than you’d like to see from him in pro ball. Chris Archer (and others) have made this work for a while, but it isn’t the sort of approach you’re looking for at the top of the draft. I’d project Rocker’s control (throwing it over the plate) as league average (50 on the 20-80 scale) which is fine for a pitcher with plus stuff, but his command (executing to specific locations) is below average (45). He tends to throw each pitch in the same/optimal location, but isn’t throwing it in a cup, in part because of head movement and audible grunts on half of his pitches in the first few innings.
Typically when scouts have to project command to improve with an elite draft prospect, they’re looking at a physically projectable, somewhat thin pitcher who will fill out and continue gaining body control. This all makes Rocker a challenge to project, given his lack of direct physical comparables.
I’d grade his fastball as a 60, his slider as a 55 to 60 depending on location/consistency, and his cutter is a 55. There’s plenty here for a No. 3 or even No. 2 starter with some improvements in these aforementioned areas. It’s a double-edged sword. Scouts are comfortable with Rocker due to years of history but are also more skeptical of him improving on these concerns since he’s been a pretty similar pitcher the last few years outside of that hot run late in 2019.
There’s also a bit of contrarianism and what-have-you-done-for-me-lately in scouting, and Rocker hasn’t been up to his late 2019 standards in 2020, 2021 or the scrimmages between.
Since basically every pitcher starts losing arm speed in their mid-20s, the question with Rocker is if his command improves as his raw stuff slowly degrades. There are data points suggesting he may not, but he also hasn’t been forced by his competition level to do that yet.
Given the raw stuff, track record, and solid health, it’s hard to imagine Rocker gets out of the top five-to-seven picks, but going toward the back end of that range is more of a discussion amongst high level scouts than most draft fans would think. His performance in SEC play, particularly contrasted with Leiter, will say a lot about his draft stock within that tight pick range.
Jack Leiter
Leiter also has a famous father, former Mets standout lefty, Al Leiter, and also was a nationally regarded prep prospect with a long scouting track record. On the summer showcase circuit, Leiter worked mostly in the low-90s, using a knockout plus curveball as his best secondary pitch — but with inconsistent command. In his draft spring, he started sitting in the mid-90s for stretches, but his command still came and went. Leiter, like Rocker, also had a high, unclear signability number that clubs didn’t appear to ever come close to meeting, surely influenced by him being older for his prep class, making him draft-eligible again in just two years at Vanderbilt.
Leiter looked improved in his short 2020 freshman season, maintaining that mid-90s velocity from his draft spring, and benefitting from Vanderbilt’s progressive approach to pitching that’s well suited to his repertoire.
In my look, Leiter’s four-seam fastball sat from 93-97 and hit 99 mph, and he relied more on a new 83-86 mph slider against Georgia State’s righty-heavy lineup than his 78-80 mph curveball, which plays better versus lefties. Leiter also appears to have shelved his changeup like Rocker, but it was always a tertiary option for him in high school.
Leiter, like Rocker, also largely works up with his backspinning fastball (grades as a future 65 for me), buries his curveball (I’d like to see more, but probably a 60 or 65), and works in and around the zone with his slider (a solid 55 that plays a key role giving a different look). I saw more variation in Leiter’s locations, particularly how he used both sides of the plate with his slider which helped his fastball play better as well. He also needs to improve his command a bit, but that’s also easier to do with a more traditionally-built athlete with a shorter college track record and a slightly cleaner delivery.
It may be unfair, but Leiter has some helpful recent comps in Walker Buehler and Max Meyer, who both have similar builds, repertoires and approaches to pitching. Contrasting this with Rocker’s recent form and lack of comps, there’s probably a little bit of bad luck in the current consensus to preferring Leiter — but there will be some substance to it if things continue like this for both of them for another month.
Leiter’s trajectory of adding an element to his game every six months or so suggests there’s more coming from him developmentally between now and draft time. SEC play this year will also be key for Leiter, mostly because he hasn’t faced lineups like he’ll see in the conference many times.
What we need to see from here
You can probably see why I, and the majority of scouts I’ve spoken with who have seen both Rocker and Leiter, lean to Leiter. It’s easier to picture him improving over the next few years.
I think you can also see why this is a close race right now. If Leiter gets shelled a couple times and Rocker holds serve and makes marginal improvements with consistent performances to match the moment, then Rocker probably goes in the first couple of picks like everyone was guessing almost two years ago.
Even if that’s not how it plays out, it only takes one team deciding either is the better option to pick. Both of them benefit from a weak college hitter class and the best college pitcher competition coming from LSU righty Jaden Hill, who needs to both stay healthy for a full season and prove he can perform in the SEC as a weekend starter. It would take some time for him to jump over the Vandy Boys.