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Kumar Rocker and Jack Leiter: A Pitching Odyssey


That’s the word I’d use to describe my feelings this weekend after witnessing the starts posted by Vanderbilt pitchers Kumar Rocker and Jack Leiter. It was hard to type that word given all the negative connotations it carries while knowing what type of precocious talents Vanderbilt has in both righthanders. But expectations were high at 7:00 PM on Friday night, and barely 24 hours later, I was left sitting in the press box at Florida Ballpark wondering what could have been.

Rocker hurled 5 innings in the Commodores 11-7 victory over the Florida Gators Friday, striking out 8 hitters but allowing four walks and posting a mediocre 49/46 strike/ball ratio. Just as concerning, the jumbo-sized righty gave up a mammoth home run to Florida slugger Kris Armstrong as well as a plethora of other well-struck balls.

Leiter fared far worse on Saturday. The New Jersey native lasted just 4 innings and exited after yielding three long balls and walking four Gators.

Let’s first examine Rocker’s outing.

When dissecting Kumar Rocker, the first order of business is establishing the lexicon. Rocker throws two breaking pitches—the more “famous” of the two resides at about 80 MPH and occasionally has the standard 12-to-6 curveball break and other times approaches the plate at more of a slant, depending on the position of Rocker’s wrist upon release of the pitch. To the trained eye, this pitch would appear to be a curveball; however, Rocker and the Vanderbilt baseball contingent refer to this pitch as a slider. Hence, this is the terminology I’ll use for the remainder of this article.

Rocker’s other “breaking pitch” travels in the 87-88 MPH range and has a much tighter break. Many would call this pitch a slider, but Rocker & Co. have labelled this offering a cutter. To each his own.

The correct terminology established, let’s delve into Rocker’s start. Because of all the attention Rocker’s three-start dip in fastball velocity (from his customary 93-95 MPH to a more sedate 90-91) garnered, it’s imperative to point out that the big guy had the heat turned on Friday. Most of his fastballs sat in the 93-94 space and some touched 95 and even 96.

Rocker kicked off his outing by fanning Gator leadoff man Jacob Young with some 93 MPH cheddar at the letters. He then hit 95-96 several times to induce a Jud Fabian pop up and whiff Armstrong. Armstrong’s AB was not without drama; however, as the brawny switch hitter hit a nuke off a 94 MPH fastball that was barely foul down the right field line.

Three things quickly became apparent as Rocker battled his way through the Florida lineup. First, the Vanderbilt ace works fast, appearing ready to fire the next pitch immediately after getting the ball back from his catcher. After decades of playing and following this sport, I’ve come to notice that a pitcher who works fast is a confident pitcher and this trait certainly holds true for Rocker. Second, Rocker was repeatedly aided by the home plate umpire’s generous strike zone, particularly on high pitches. This helped him garner several high-fastball strikes. Finally, Rocker pitches with emotion. There was an assortment of F-bombs, fist pumps, and scowls. In short, the kid left it all on the mound Friday.

As his outing progressed, Rocker mainly toggled between his fastball, which stayed true at 93-94 MPH for his entire 5-inning stint, and his slider, and sprinkled in some cutters when necessary. Though Rocker collected a bunch of Ks, his command was off and several Gator hitters took advantage.

Nathan Hickey, Florida’s second-place hitter, drove a 94 MPH center-cut heater to center field in the 1st inning for a line drive single.

Two batters later, as I alluded to above, Rocker grooved a 93 MPH heater to Armstrong, which landed barely foul some 400 feet away.

In the 2nd inning, Kendrick Calilao turned around a Rocker fastball and hit a loud flyout to center field.

In the 4th, Rocker once again left a fastball up to Armstrong and this time Armstrong wasn’t as forgiving, launching a 400+ foot missile that left the bat at 108 MPH.

One batter later, true freshman Sterlin Thompson tagged a 95 MPH waist-high fastball for a loud lineout to right field.

In that same inning, Josh Rivera swatted a Rocker fastball for a screaming one hopper to Vandy SS Carter Young. Young made a great play on the ball but couldn’t throw out Rivera.

If you think you’re seeing a pattern here, it’s because you are. Though Rocker was able to get a number of swinging strikes on his high-octane fastball, it got hit hard when his command of the pitch faltered.

In addition to giving up hard contact when his fastball command was lacking, Rocker’s difficulty controlling the pitch was the primary culprit for the four walks he surrendered. An example of this came in the 5th inning when Rocker walked Fabian on a 3-0 fastball. In this instance, as well as throughout most of the game, when Rocker missed with the fastball it was to his glove side.

As in most of his starts this season, Rocker had more luck with his slider. What makes this pitch so effective, is Rocker’s ability to “tunnel” it with his fastball. This means the ball leaves his hand in nearly the exact same fashion with both pitches, making it nearly impossible for the hitter to discern between the two offerings.

Rocker’s adroitness with the slider induced a number of swings-and-misses and also resulted in multiple called strikes. In the 3rd inning, Jordan Carrion, still reeling from swinging through a high hard one, took a high slider for strike 3. Then Armstrong and Thompson went down back-to-back waving at 80 MPH sliders to end the 5th.

Though Rocker had his moments like the ones featured immediately above, his inconsistent fastball command and control are an important blemish that will have to be ironed out for him to reach his ultimate ceiling of front-of-the-MLB-rotation workhorse.

Let’s now look at Leiter’s outing.

Until his start on April 17, Jack Leiter’s spring had been the season dreams are made of. The 6-01/205 righty had dominated in each of his starts, and notched a 20-inning hitless streak, which, of course, included the 9-inning no-hitter he tossed on March 21 against South Carolina.

Much of Leiter’s early success this season was predicated on his devastating fastball, which has been called the best pitch in the draft by scouts and analysts alike. In his well-thought out article from April 6, Fangraphs’ Justin Choi explains in great detail the keys to Leiter’s fabled heater. In a nutshell, Leiter’s low release height of 5.2 feet combined with his elite 6.6-foot extension, 95% spin efficiency, and 19.9-inch vertical break all combine to make his fastball torturous for collegiate hitters.

However, after never having thrown more than approximately 60 innings in any one spring season, Vandy’s Saturday starter has seemingly hit a wall. He entered this start having given up seven earned runs and five homers in his last two outings after yielding just three of the former and one of the latter in his first eight appearances. I was curious to see if this trend would continue.

Unfortunately, I didn’t have long to wait. Leiter kicked off his act with a series of 94 MPH fastballs to the Gator table setter Young and walked him on five pitches. He then walked Hickey on five pitches. Up to the plate strode Fabian.

As I’ll discuss in a subsequent article, it hasn’t been the kindest of springs for Fabian. The Florida center fielder and three-place hitter entered the season as a possible candidate to go first overall in the upcoming July draft, but a strikeout rate that is parked near 30 percent may force him to fall out of the 1st round altogether. That said, he has a lightning-quick bat and one of the college game’s top average exit velocities. This would be no picnic for Jersey Jack.

Leiter opened the Fabian at bat with an 80 MPH curve, which was out of the zone. He then opted for two fastballs—the first at 91, the second at 93. Fabian took both for strikes. Then Fabian implemented his new two-strike strategy, widening his base to prevent him from getting out on his front leg on outside sliders. Leiter’s 1-2 pitch wasn’t a slider, but it didn’t matter. It was a 94 MPH fastball middle in that Fabian deposited in the left field berm. 3-0 Florida.

Leiter had a much better 2nd inning, striking out the side after a Jordan Butler single. During this brief show of force he was primarily a two-pitch pitcher, using a 78-80 MPH deuce early in the count to set up his 91-93 MPH heater that elicited a swinging third strike to Rivera, Colby Halter, and Young.

In the 3rd, Leiter broke out his 83-85 MPH slider. He employed those early to Hickey then got the Gators catcher to fly out to center field off some 97 MPH cheese, his fastest pitch of the night. Suddenly, Fabian began to make his way to the plate again.

Early in the at bat, Leiter went mano y mano with the 20-year-old Fabian, firing pellets at 96 and 97. Then, with two strikes, Leiter went with an 83 MPH slider on the inner half of the plate. And once again there was a mad scramble amongst the fans in the left field berm for a souvenir.

Two batters later, Kirby McMullen made Leiter pay for another slider, this one at 84 MPH, when he jacked it out of the park.

The most revealing at bat came in the 4th inning against Rivera. If you recall, Leiter had already bullied Rivera with his fastball back in the 2nd and was doing the same again with heat clocked between 93 and 95 MPH. However, instead of finishing off the Gator infielder with some more high Provolone, Leiter switched gears and went with a curve. Rivera promptly belted a line drive single to left field.

This at bat was so informative for two reasons. First, the fastball has been Leiter’s bread and butter all season. With its otherworldly metrics, it’s simply too much for nearly all college hitters to handle. When right. But has Leiter’s heavy workload (he passed the 60 IP mark on Saturday) taken a toll on his heater and forced him to revert to his secondary offerings?

Second, Leiter’s struggles on Saturday with his curve and slider reinforce the difficulties he has had with both of these pitches for a good part of the spring. When Leiter was able to use his fastball to force opposing hitters into submission, his inconsistent secondaries were merely a footnote; however, if his fastball has indeed lost some juice, this inconsistency will become a more prevalent theme.

Though Rocker and Leiter’s starts were far less than what both pitchers are capable of, it’s vital to note that each was a mere data point. Taking each pitcher’s full body of work into consideration, it’s easy to see why both will be premium draft picks in two months.

Kumar Rocker has starred against top hitters for years. He could have been a 1st rounder out of high school then threw a no-hitter (with 19 strikeouts) against Duke in a Super Regional elimination game as a freshman. And he does have a sterling 1.90 ERA and 97/19 K/BB ratio in 69 innings this season.

As outstanding as Rocker has been, many scouts will tell you Jack Leiter is even better. When working with his full toolset, even the most advanced amateur hitters have no shot against his supersonic fastball, let alone his other three pitches, all of which grade out as at least above average.

Bottom line: when Rocker and Leiter are picked in the top half dozen picks in July, the teams that select them will be thrilled to have landed the two best available arms in the country. And the “underwhelming” starts I witnessed this weekend will be remembered as small bumps in the road.

If they’re even remembered at all.


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