“” Basics of Pitch Design Using Rapsodo - Driveline Baseball

Basics of Pitch Design Using Rapsodo

| Pitch Design
Reading Time: 8 minutes

By this point, you’ve probably heard a lot about pitch design.

But how exactly do we go about designing pitches?

What are we looking for when working on a pitch?

What tools do we use?

How do we do it?

The most important tool we have in house is the Rapsodo. It provides instant feedback on the pitch’s velocity, spin rate, spin axis, and pitch break. This gives insight into what the pitch is actually doing, and by comparing to other MLB pitches, how it can be improved.

We also use a few other tools in order help our athletes get feedback on what they are doing right or wrong with a pitch. Spin Axis balls, which we simply mark up with a sharpie, provide a great visual tool to show an athlete what the spin axis of their pitch is.

We also use the Edgertronic high speed camera in order to see what exactly the fingers are doing at release point. This enables athletes to visually see what their hand and fingers are doing when they release the ball, and what they need to do to improve the pitch.


Using this trifecta of tools, the Rapsodo, spin axis balls, and high speed video, we have had a lot of success with pitch development in a relatively short period of time.

As mentioned previously the key to off-speed pitches isn’t the total spin, but the relationship between the spin rate and a pitch’s spin axis.

This is what makes Rapsodo so valuable to pitch development. Its camera can give us not only total spin but useful spin, the amount of spin that is lined up with the axis.

When developing a pitch, the useful spin metric is going to be your best friend.


Personal Examples of Pitch Design

Slider Pitch Design

Casey Weathers has been a main stay at Driveline Baseball since he moved up here to train in 2014.  Arriving here with significant arm pain and throwing in the high-80s, he has gotten himself healthy and throwing hard again. Besides being a beloved member of the Driveline family, he can also do this with a baseball:


He throws hard. But this off-season his major goal was developing a better secondary pitch. The past few years of Casey’s training focused primarily on healthy and velocity development, but Casey knew his second offering needed some work.

He’s always thrown a slider, but it was never really something he had ever tried to work on improving, nor did he have the necessary tools to improve it.

Analyzing his current repetoire and velocity, arm slot and we decided that a pure gyrospin slider was the best pitch to develop. It played the best off his fastball rather than a loopier breaking pitch like a curve or slurve. 

Pure gyrospin is the typical spin axis of many quality big league sliders. This meant that on Rapsodo, the pitch would have a spin efficiency close to 0%. What does a gyrospin slider look like?

There was no guarantee Casey’s slider would move like that as arm slot, mechanics, and a wealth of other factors all play a role, but the gyrospin slider as the goal at least we had a target to improve against.

Casey’s first sliders had a spin efficiency of around 20-30%. Pitch design sessions are mostly just trial and error, as Casey worked to find which mental or physical cues and grips felt best and resulted in the best pitch. In addition to the “sniff test” (if the pitch looks good to the naked eye), we used the Rapsodo as feedback to measure total & useful spin.

The instant reads allowed good cues to be adopted quickly and tweaked and bad cues to be rejected, improving the accuracy of the feedback over time. To further tighten the feedback loop, we added Edgertronic and spin axis balls. 

Using the Edgertronic and spin axis balls to determine the spin axis, Casey could see how his hand and wrist position would change pitch to pitch. This provided visual feedback on how his grip affected the spin of the pitch, in addition to the data feedback from the Rapsodo.

With all this going at once, the feedback loop was tight and accurate. An example discussion follows:

“Ok so you sort of hooked your wrist on that last one, causing it to spin more like a slurve or a bad curveball. Don’t hook it, just let the grip do it’s work.”

“So just stay on the side of the ball and throw it like a football.”

“Throwing the ball like a football” was a cue that really seemed to click with Casey (we arrived there after several others did not click). The ‘traditional’ slider grip, the index & middle finger on the horseshoes of the baseball, didn’t give the desired feel or spin efficiency changes. Casey essentially gripped it like a fastball, cutting the ball in half with his thumb and pointer finger and resting his middle finger on the outside of the ball. Then he threw it like a football.

An underrated bonus of using the Rapsodo and having this back-and-forth with the athlete is finding out which cues & visualization techniques work best for them. Throwing a new pitch is more complex than just a new grip, and athletes are going to have different interpretations of the same cue. Using the Rapsodo in this way can create a great feedback loop between what the athlete feels and what the data says the ball is actually doing.

Eventually, Casey was able to develop a tight slider that has a consistent spin efficiency around 5%. He was given the tools to do it, all it took was the right direction and plenty of repetitions.


Curveball & Change-up Pitch Design

This iterative pitch design method doesn’t just work for sliders. Because it is a fluid process with a discrete goal, it works for any pitch.

This off-season, we had pitchers develop a curveball (Dean Jackson) and a splitter, not to mention many other pitchers who learned made slight pitch adjustments after using the Rapsodo.

Dean wanted to improve the spin efficiency of his curveball so it would have more movement. Using the same methods as above (set a goal and experiment), Dean was able to improve the spin efficiency of his curveball from around 80% to above 90%, as well as his consistency with the pitch.

With Rapsodo providing the feedback of useful spin, he was also able to play around with different cues to improve the pitch.

First, he drew a line in sharpie around the ball on the specific spin axis he wanted to achieve. Then he played catch with a partner, throwing only that pitch, getting his own visual feedback and confirmation from his throwing partner.

Once he started to get a feel for it there, he started throwing it on Rapsodo with a bit higher intent to see spin axis, as well as the spin rate.

Using Edgertronic video he could see what his hand was doing at release when he threw a bad one. More often than not, his middle finger would drag down the ball at the last second, giving the ball an unstable, and incorrect, spin axis. He was able to correct this by slightly adjusting his grip, letting his middle finger just come off the ball, rather than dragging along the ball.


3 different pitches, 1 method. Dean improved an already good pitch in his arsenal, and Casey tried to make a not-great slider much better. All 3 pitchers worked on different pitches, but the method of developing, testing and refining was the same.


Pitch design is a hugely subjective process with plenty of trial and error. The way one athlete develops a pitch may be totally different from another. A grip that works for one pitcher may not feel good to another. Each athlete will have to find the grip, cue, and feel of a pitch on their own through some amount of trial and error.


The data (Rapsodo), visualization (high-speed video and spin axis balls), and feel all work together to help an athlete develop a pitch. Beyond that it is up to the athlete to interpret the information and make adjustments.

Yes, pitch design is a very individualized process, and it takes a lot of iterations to develop a pitch. Being able to provide athletes with the tools to provide as much information and feedback to the athlete makes it that much easier.

This article was written by Lead Engineer Joe Marsh

Check out what else we know about everything spin rate / pitch design here.

Comment section

  1. Blake T -

    Are you guys going to do an article on horizontal movement/vertical movement using the rapsodo and different pitches?

    • Driveline Baseball -

      We don’t have any plans to write an article specifically on that, but we will definitely go more in depth with pitch design.

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