Paul Skenes and The Blueprint for a 100 MPH Fastball with "Poor Shape"

The Formula for Whiffs and HR Prevention Without Elite Carry

Paul Skenes is a fascinating case study; he throws triple digits, but his fastball shape has led to some questions as to how that might play in the major leagues. Is he the best pitching prospect to come out of the NCAA since Strasburg and Cole? Or is he “only” going to be a #2/#3 starter?

Do I have enough data to speak confidently about his fastball shape? Yes. It doesn’t have great shape, in terms of Induced Vertical Break. But I also don’t think it matters, and I’ll show you some data that explains why. Skenes might just provide the blueprint for guys that throw really hard, but don’t get rise on their fastballs.

Location, Location, Location

Whiff / Swing by Height at Plate, Split by Rise

I classified every MLB 4S fastball in the HawkEye era as either Elite (18”+ IVB/Flight), Plus (>16”), Meh (>14”), and Oof for everything else. Skenes is in the “Oof” category, which I have intentionally named in a pejorative fashion. The buckets don’t matter per se, but let’s analyze this chart:

1. Shape matters! Having elite carry is great. Skenese is more horizontal, which doesn’t generate whiffs for fastballs.

2. Once we get a couple of inches above the zone, shape doesn’t matter at all. Just 2 inches above the zone, even Oof shapes get as many whiffs as Elite ones.

3. As we approach the top of the zone, only Elite carry is a differentiator, but anything below that doesn’t matter as much.

Velocity

Elite velo (97+) plays best up in the zone. I’ve filtered to pitches +/- 6 inches from the center of the plate. But what if we’re including elite carry fastballs?

We get the same trend, even for more generic fastball shapes.

Elite velo at the top of the zone is great. We don’t have a ton of data on 100 MPH+ at the top of the zone, but I would surmise it would play quite well, regardless of shape.

Contact Management

HR/Ball In Play, By Velo Bucket

We see that elite velo makes it harder for batters to hit HRs. HR% is much higher in the top half of the zone, however, elite velocity mitigates this risk, quite substantially.

For centre-cut pitches vertically, Elite velo reduces HRs from about 9% per BIP to 5.4%, which is an enormous difference. A pitcher with elite velo can comfortably attack the upper half of the zone, knowing their risk of giving up a HR is vastly reduced compared to other pitchers.

BAD SHAPE = GOOD HOME RUN PREVENTION

Apologies for the all caps, but I’ve left the key chart for last:

Having less rise makes it harder for batters to lift the ball for home runs. This is because launch angles are correlated to how much batters expect the ball to rise and how much it does. Skenes is in the “Oof” bucket of IVB/F and batters will have lower launch angles against his shape.

Watch This Skenes Highlight Reel:

You’ll see a lot of Ks with Skenes throwing 100 up and away to batters. I watched a lot of Skenes video, and this appears to be a deliberate approach of his.

Also, he does this really weird thing where he is on extremely different sides of the rubber vs L and R. This results in a release point that is almost 2 feet different.

It’s quite unprecedented, only 23 MLB pitcher seasons in the HawkEye era have even shifted by more than a foot on average. Matt Strahm is the only other guy who really does this. To me, this is evidence of elite command, but I am open to other interpretations.

Putting it All Together

Skenes knows what he’s doing. His natural mechanics give him a horizontal fastball rather than a vertical one. Pitchers don’t really want to mess with their mechanics (nor should they for the most part), so he found an approach that works.

A 100 MPH fastball, with Skenes’ shape, to the top of the zone, will be not only be a whiff machine, but also well above average at preventing home runs. If we’re looking at this from a FIP perspective, we’re talking about a guy who will get Ks, avoid walks and avoid HRs, just based on the fastball and where he throws it. Oh, and scouts say he has an 80 slider as well. Skenes is going to be fun. Time to get hyped.