The CWS shows bulletspin--rewriting the book on movement pitches

[malletfinger]

Here are the Rapsodo charts: https://cdn.shopify.com/s/files/1/0...ll-Elite-Pitching-Guide_2021.pdf?v=1660038271

I'm curious about what this Rapsodo chart is saying about fastballs:


An average pitcher in college could get their fastballs to move 6 inches in a vertical direction and/or 6 inches in the horizontal plane at what seems like spin rates on the lower end of the spectrum for a rise or a curve... My DD's fastball is not close to this... Is this chart stating there are average college pitchers consistently throwing this kind of fastball?

 

[Northball]

I'm beginning to think NASA should get involved. Pitching lane needed at the ISS. No gravity, but does have atmosphere. Then we have true effects of spin axis determining trajectory. If you thought Bahl already leaps...

 

[Gtrips07]

I'm beginning to think NASA should get involved. Pitching lane needed at the ISS. No gravity, but does have atmosphere. Then we have true effects of spin axis determining trajectory. If you thought Bahl already leaps...

Do they have skid marks on the ISS?

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[ArmWhip]

I'm curious about what this Rapsodo chart is saying about fastballs:
View attachment 28556

An average pitcher in college could get their fastballs to move 6 inches in a vertical direction and/or 6 inches in the horizontal plane at what seems like spin rates on the lower end of the spectrum for a rise or a curve... My DD's fastball is not close to this... Is this chart stating there are average college pitchers consistently throwing this kind of fastball?

There are some questions that are not answered on the Rapsodo website. What kind of spin do fastballs and change ups have, in their definition of each one? What is the direction of the horizontal break? The two things are related and if you're trying to understand what is going on you need that information.

 

[malletfinger]

There are some questions that are not answered on the Rapsodo website. What kind of spin do fastballs and change ups have, in their definition of each one? What is the direction of the horizontal break? The two things are related and if you're trying to understand what is going on you need that information.

Yes, I guess we're left groping for some definitions, as well as distributions of results (e.g. what percentage moved 1" horizontally vs 3" vs 6", etc). In the absence of this info, we can do some mental gymnastics for fun though:

4-seam fastball spins would be predominantly 12-6 (topspin) or bullet spin (or some tilted version), with some smaller distribution of "screwball" spin. I doubt a 12-6 would produce 6" of horizontal break. A tilted bullet might produce a horizontal break, but it's hard to picture it being in similar in range of movement (6") as a curve. Same goes for a screwball spin vs a curve.

Perhaps I just haven't watched enough pitchers from behind home.

 

[LEsoftballdad]

Yes, I guess we're left groping for some definitions, as well as distributions of results (e.g. what percentage moved 1" horizontally vs 3" vs 6", etc). In the absence of this info, we can do some mental gymnastics for fun though:

4-seam fastball spins would be predominantly 12-6 (topspin) or bullet spin (or some tilted version), with some smaller distribution of "screwball" spin. I doubt a 12-6 would produce 6" of horizontal break. A tilted bullet might produce a horizontal break, but it's hard to picture it being in similar in range of movement (6") as a curve. Same goes for a screwball spin vs a curve.

Perhaps I just haven't watched enough pitchers from behind home.

The Diamond Kinetics ball does a great job showing spin speed and rotation. Unfortunately, it's way off in velocity.

 

[ArmWhip]

I'm curious about what this Rapsodo chart is saying about fastballs:
View attachment 28556

An average pitcher in college could get their fastballs to move 6 inches in a vertical direction and/or 6 inches in the horizontal plane at what seems like spin rates on the lower end of the spectrum for a rise or a curve... My DD's fastball is not close to this... Is this chart stating there are average college pitchers consistently throwing this kind of fastball?

Rapsodo measures spin efficiency, in order to do this they have to define what that spin is. What is the spin on a 100% efficient fastball, (or change up)? And the other thing I'm curious about is whether their side spin efficiency (curve, screw) is measured using the balls real trajectory or measured using a theoretical flight path parallel to the ground (horizontal). All pitches have a downward trajectory, especially side spin pitches which generally have less velocity. This is what makes a slider break.

 

[jfitch12]

Rapsodo measures spin efficiency, in order to do this they have to define what that spin is. What is the spin on a 100% efficient fastball, (or change up)? And the other thing I'm curious about is whether their side spin efficiency (curve, screw) is measured using the balls real trajectory or measured using a theoretical flight path parallel to the ground (horizontal). All pitches have a downward trajectory, especially side spin pitches which generally have less velocity. This is what makes a slider break.

100% efficient just means that there is 0% gyrospin. So a ball that spins straight down, straight up, straight sideways, or anything between (11-5, 10-4, etc.) all will be 100% efficient. In other words, imagine a coordinate plane where the x-axis runs from 1st base to 3rd, the y-axis runs from second to home, and the z-axis runs from the ground to the sky. A pitch will be 100% efficient if the ball’s axis of rotation has no y component. Conversely, a pitch will be 0% efficient if the axis of rotation has no z and no x component (the axis points directly at home plate).

I believe (but am not positive) Rapsodo uses actual pitch trajectory and speed to extrapolate spin rate and efficiency. For that reason, individual pitches (usually rise balls) will display an efficiency and axis on the Rapsodo that bears no resemblance to the pitch thrown by the pitcher. If you look at averages, the machine is more accurate, but often the extrapolation is wrong for individual pitches.

If you have ever caught a slider (no different than a curve in softball), it has a large proportion of gyrospin, but it is by no means pure gyrospin (or 0% efficient). The axis of rotation on a slider with “sweep” will be “tipped up” from the catcher’s perspective (it has more side spin), whereas the axis of rotation on a slider with “depth” will be “tipped to the side” from the catcher’s perspective (it has more down spin), relative to a pitch with pure gyrospin. That combined with the trajectory down the mound (I believe) accounts for the movement, and the large variation in movement profiles that you can see on sliders (from true downers that are almost curves to true sweepers that have very little depth).



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[jfitch12]

Yes, I guess we're left groping for some definitions, as well as distributions of results (e.g. what percentage moved 1" horizontally vs 3" vs 6", etc). In the absence of this info, we can do some mental gymnastics for fun though:

4-seam fastball spins would be predominantly 12-6 (topspin) or bullet spin (or some tilted version), with some smaller distribution of "screwball" spin. I doubt a 12-6 would produce 6" of horizontal break. A tilted bullet might produce a horizontal break, but it's hard to picture it being in similar in range of movement (6") as a curve. Same goes for a screwball spin vs a curve.

Perhaps I just haven't watched enough pitchers from behind home.

You are right that the Rapsodo charts really do not correlate the spin rate, speed, spin efficiency, or movement in a meaningful way. What is useful (I think) is really only the absolute movement numbers. If you have someone with a rise consistently above +6 VB (or a drop that is consistently -8), you have a pitch that will be effective in college and largely unhittable in high school. So the Rapsodo is helpful in figuring out what kind of pitcher you are (primarily up or down, east or west), and how your movement pitches stack up to others at your age or level of competition, but the details are not nearly as valuable (and not really trainable—how do you increase spin rate, for example, other than using Gorilla Grip?) And as I mentioned above, there are often big discrepancies between what the machine reads and the actual pitch, so trying to use Rapsodo on a pitch by pitch basis to fix spin axis (rather than using visual evidence) can be hard. The machine’s best use is in telling you how much the ball moved, not why it moved, or giving you averages that are accurate over a large number of pitches.


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