Already MLB's BEST Slider?! | Kumar Rocker Breakdown

Rocker's Release Characteristics The Rangers are calling up Kumar Rocker for his MLB debut. He's one of the fastest rising pitching prospects that I can remember. He dominated at Vanderbilt in 2021. His subsequent two seasons were marred by injury. When he returned this season from Tommy John surgery, he has crushed hitters. So let's break down his pitch data. Rocker stands 6 foot five with a 5 foot 8 release height. That's a hair below average on the release height side of things. Usually with big frame guys we see release heights that are above average, but Rocker has a pretty low slot and perhaps more important, he has plus extension down the mound at just under 7 feet. That means his release point is closer to the hitter than about 92% of other right-handed pitchers. Rocker's horizontal release point isn't really an outlier, but because of his frame and his arm length, he gets over towards the third base side of the rubber further than about 80% of MLB right-handed pitchers. Mix all of these release characteristics together, and as I detailed in a video I just made about deception, I think it's fair to say that he possesses somebody deception in terms of how he moves, and overall that helps his stuff perform above what the underlying shapes suggest. Slider Shape and Performance Speaking of those shapes, let's start with his primary breaking ball. This thing is insane. He generated a 42% swinging strike rate on the pitch at AAA 42%. The average swinging strike rate for breaking balls is around 16%, and 20% is great. 3/4 of the time a hitter swung at his breaker, they missed. That's more than double what you'd expect. I get him highlighting small sample stuff at AAA in terms of results, but nearly all the data from AAA lines up with what we saw at AA, so our sample is more like 7 starts. The shape of his breaking ball is pretty distinct. It's 85 mph with -5 inches of induced vertical brake and under an inch of glove side movement. This is what it looks like on a pitch plot. Most sliders are somewhere over here. Sweepers are over here on the left because of their glove side movement and curve balls have drop in sweep so they're usually down here. Death balls are slightly more efficient gyro sliders, and that added efficiency creates more downward break. It's a very vertical shape and the pitch drops more. Think of a curveball top spin out of hand right stiff wrists popping out and spinning something like this on the way to the plate. A pure gyro sliders thrown off him like this, maybe not totally pure bullet spin out of hand. Guys usually are behind the ball pretty well, but this is a resulting spin is what you're looking at something like this for Kumarakar, he throws his slider like a bullet slider. I just think he's clipping the front of the ball slightly more such that you get an in between kind of spin that adds drop to the pitch. Not as much as a curveball in the advantage being because there's not as much drop and it's not pure top spin. He's able to throw the pitch hard around 85 mph and create this really nice combination of both drop and velocity. Now, I do believe Rocker calls this pitch a curveball. So when you see it on stack cast, it's going to track it as a curve and not to tell Rocker that he's wrong. But I don't really care what it's called. I care kind of more how it moves from an analysis standpoint, especially from a modeling standpoint. That's why I prefer to call it a slider, for the simple reason that the resulting shape and velocity line up with other sliders, in my opinion, more than it does other curveballs, which you saw in our plot. Regardless of all that classification, this pitch will have one of the steepest approach angles into the zone of any breaking ball. In MLB, we can measure that approach angle through something called Vertical Approach angle, or VAA. It's literally the angle the ball is approaching the plate. Kumar's will be around -9 point 1° at 85 mph. I found basically three other pitches above 85 mph with a steeper approach into the zone and they're all really good pitches from relievers. Juan Durans curveball, Luke Jacksons breaker, P Fairbanks slider. Fairbanks being one of the original death ball guys. Now VAA is dependent on location, so the stat is somewhat communicating that Rocker is getting the pitch down in the strike zone. But it's also confirming for us that his combination of drop in velocity on this pitch is pretty distinct. He throws the slider around 40% of the time to either handedness of hitter. Because of the shape, it's pretty platoon neutral and as you can see from the heat maps of his slider at AAA, he's around the zone a lot with the pitch, which makes the results he got on this offering even more impressive. What are Stuff+ Models Missing? Despite all the industry praise on the pitch, I actually think it's still being undersold stuff. Models are telling us that it has drop it and has velocity. We just pointed that out. That's how you get it to a plus pitch. You then have to square that plus pitch with plus plus 280 grade results on the offering. I'm going to do that in two ways. First off, from the body deception angle I mentioned earlier, Kumar's a big guy. He gets down the mound really well. It's a low slot. I almost wonder whether you expect sweep from that slot and instead you get a very vertical downward shape. But the other element in this mix is more interesting to me, the visual the pitch creates. This is something that I don't really think stuff models capture, and I don't really think anybody can capture it. But pure hitter feedback or maybe electronic cameras behind home plate looking out at the pitcher to discern how that ball spins and what hitters perceive, literally perceive, and that first, say, 60% of ball flight when they're making their decision on the offering. There's an old concept called spin mirroring, which is the idea that curveball spin mirrors fastball spin. It's just in different directions. Maybe there's some blurring of that going on between the two pitches. I just know based on the results here that it's a nasty pitch and there's something going on beyond what stuff is capturing. The crux in all this is that Major League Baseball hitters are different than minor league hitters. So I think we're going to learn pretty quickly how good this pitch is. And my bet right now is that it's elite Rocker also has two fastballs, A4 seamer and a sinker. Four-Seam Fastball The four seamer averages 98 mph with 12 inches vertical brake and 10 1/2 inches of horizontal movement or arm side movement. The shape isn't great. It's what you'd call dead zone, which is referring to a section of movement plots where there are a lot of unsuccessful fastball shapes historically. You can see that in this plot right here. The blue concentrations are those pitches that perform below Major League average historically, and the red are the good pitches. The main thing to realize with shape in dead zone is that velocity influences how big this dead zone shape is. The harder you throw, the more you can get away with bad shapes. Velocity buys margin for error. Watch what happens to the blue area when I go from fastballs in the 92 to 95 mile per hour bucket to fastballs in the 96 to 99 mile per hour bucket. The blue gets smaller, there's less worse pitches. We had this debate in the industry with Paul Skeens, who was rumored to have a bad fastball shape. And sure, you can argue his fastball shape is still bad, but it's worked at the Major League level. These more horizontal, less vert shapes do a pretty good job limiting barrels, even if they're not generating swing miss. And we see that with rocker shape through AA and AAA, albeit for a shorter period of time. Even as I defend this pitch as not being bad, I don't really think it's plus. It's probably somewhere more around average and it's getting there purely on the velocity side of things. I expect it to allow the most damage in his mix. So what we're looking at probably because he throws his pitch more to the left-handed hitters, is a pitcher with natural splits, better versus righties, worse versus lefties. And the counter to that would just be throw your slider like 70% of the time. We'll see exactly what he does. He's probably still going to need some fastballs to succeed. Rocker throws this 4 seam about 40% of the time to lefties and just about 25% of the time to righties. From a location standpoint, he's throwing the four seam inside to lefties, which I like because it's hard. He's also flashing it up in the zone for whiffs. Sinker His sinker is perhaps the more intriguing weapon. It's 97 mph with 9 inches of vertical brake and 15 inches of arm side movement. He throws it 26% of the time against righties and barely at all to lefties. Enoceris's stuff model really likes this pitch, seeing it squarely above his four seam. I'd guess this is heavily velocity based in the strong grade. There also aren't a lot of sinkers above 96 mph in the first place. In terms of location, he's inside with his pitch to righties. No surprise. When you combine his four seam and sinker to righties, you see that he's splitting the plate inside and away, which I like from an approach standpoint. If you think righties touch anything against him, I don't think it's going to be the sinker. I bet it's the four seam away that more misses back over the plate. That's why there's a world in which the sinker starts to dominate his usage relative to his four seam over time. Let's say it jumps from the 26% he throws it right now to righties to 40% and that four seam becomes more of a late count with pitch comes down to 10% or so. I bet his net results versus righties would be better with this approach. Changeup and Cutter Beyond the sinker, we also have a change up that he hasn't really thrown a ton, but the shape looks solid on it. Primarily again because it's really hard. It's 92 mph with 6.5 inches vertical brake and 14 inches of arm side movement. Once again, a pretty standard shape that grades out well because of velocity. He's throwing a few of these to righties below 5% total. It's mainly a deep count lefty pitch for him. This is probably the toughest pitch in his mix to analyze because we don't have almost any sample on it. Based on a slot and fastball characteristics, I'd be pretty surprised if there isn't at least an average change up in his tank. Low slot guys like him usually don't have a ton of trouble creating drop on a pitch and rocker, as I've spoken about numerous times already, has thrown everything really hard. Here's Enosaurus's stuff board one more time with locations to give an overview of what we just talked about. This time I'll add in my personal assessments of his shapes. I think it's an average fastball, A+ sinker plus plus to 80 slider. And for the change up, I'm just going to call it average for now because we don't have a ton of sample and the net here on the command side looks like it will be above average. Rocker also mixed in a cutter at AA, but we didn't see this pitch at AAA. It was around 4 to 5 inches of vertical brake with zero to 1 inches of sweep. It's basically another slider as opposed to a pure cutter shape. And again, that hard drop combination that he seems to have a knack for would allow this pitch probably degrade as plus, although we didn't see it at triple AI know it's in the tank and perhaps we see it down the road versus left-handed hitters. What Could Rocker Change? In terms of what could change or develop with Kumar Akra, I'll go to two things. Number one is change up development. This is a pretty layup answer given the four Seaman's his worst fastball and he throws the pitch more to left. He's focusing on another weapon that can help against that. Handedness is low hanging fruit. He just hasn't really thrown the pitch a ton. It's hard. The shape looks fine. I think there'll be some natural progression of this offering over time #2 what about adding a splinker? I get that stuff, plus really likes the sinker, but what would make it blow up in models is if you could create more drop and hold velocity around 95 to 96 instead of 97. Paul Skeens and Jose Soriano are both pitchers who throw splinkers and actually compare pretty well to Kumaraka from a shape standpoint. The key to most splinters seems to be with of fingers. With a guy like Soriano, he's going towards more of a splitter style grip with wide fingers and just throwing it really hard. Skeens is more on a true sinker grip inside of the horseshoe here, again with wide fingers. Both of these guys are able to create pretty crazy drop velocity combinations. I'd be pretty fascinated to see Rocker play with this Paul Skeens splinter grip and see what happens to his shapes. I'd say you can even toy with the Paul Skein's change of shape, which has been pretty exceptional despite the fact that he hasn't thrown it a lot. Just copying Paul skeins can't really be a bad thing. How Good is Rocker? Back at the beginning of August, I ranked Kumarakur 14th on my Top 40 pitching prospects list. At the time I thought this was a really aggressive rank. I just kind of kept moving him up as I saw what I thought was exceptional stuff in the minor leagues. Since then we've had about a month and a half of him continuing to dominate. So if I could re rank right now, I'd probably have him inside my top seven or eight right next to a guy like Rhett Ladder who's already he had success at the Major League level. Rocker probably has a higher ceiling than a guy like Rhett louder because he throws so much harder, but in that same sphere of having good floor, an exceptional ceiling. This is the top 10 pitching prospect in baseball. You could see it from the velocity side. The slider is incredible. I'm fascinated to see how a Major League hitters react to his stuff. That's going to tell us a lot. I think about his long term viability and I'll also point out that if he struggles right off the bat, I'm not going to panic. I kind of panicked with Jack Leiter when I made a video on him earlier this season and I regret panicking on him because I really liked him and I I still think he's coming into form despite some location problems. There's other guys that have come up this year like a David Festa, for example, from the Twins, Zebby Matthews, who both struggled. I still really like both of those guys going forward as well. So let's have some patience with Kumarakar into next season. He's a really fun pitcher. There's some elements here that are very distinct among other pitching prospects. This is one of the best pitching prospects in the game. Enjoy his Major League debut.