Every Pitch Design Metric Explained

In today's article, I layout the foundational pieces of information you need to understand in order to get started in pitch design. We will be covering what these metrics mean, how you can use them and provide you with links to dive deeper if you'd like.

Over on the YouTube channel a few weeks back I put together a video describing all of the pitch design metrics you need to understand in order to get started. It’s one I think anyone new to this industry could find incredibly useful. In today’s blog post, I want to dive a little deeper into that information by describing what some of these metrics are, how they can be applied, and finally wrap it all up with how they interact with each other.

The metrics we will be covering today include:

As you’ll notice, each of the items in that list are linked to in-depth videos on each topic. If you read through this and you’d like to dive into any one metric definitely give those videos a watch! Let’s jump into it.

Spin Rate

Starting with one of the basics, spin rate. Spin rate is the measure of how fast a pitch is spinning measured in revolutions per minute (RPM). Spin rate is largely believed to be a constant for each pitcher - meaning that it cannot be trained to be manipulated to a higher number without the use of an illegal substance (such as pine tar). That’s a very important aspect of this metric, because it is not so much an evaluation of how good or bad a pitcher is… But instead it tells a story of where each pitcher can best attack the zone in order to see success during games.

Each pitch falls due to gravity, but a pitcher’s spin rate helps describe how much each pitch’s movement profile will alter from that pull. For example, the average MLB fastball comes in with a spin rate of about 2200 RPMs. This is the average, what most hitter’s are used to seeing, so if you deviate from that average drastically your pitches will perform better. Pitch design is all about trying to deviate from what hitter’s are used to. If you have an above average spin rate on your fastball, let’s say 2500 RPMs, then your pitches are going to “fall less” than a pitcher with average spin rate. That’s very valuable information then because if your fastball “falls less” than the average pitcher’s fastball you should want to pitch up in the zone so hitter’s are constantly swinging under your pitches.

On the flip side, pitcher’s with below average spin rate on their fastballs want to pitch low in the zone in order to pitch under opposing hitter’s bats because they are used to pitches not dropping as much as yours might.

But spin rate doesn’t tell the whole story when you’re working at different levels of the game, a MLB pitcher’s spin rate is going to be different than a high school pitcher’s spin rate. That is because it is highly correlated with a pitcher’s velocity. As an athlete matures, they will throw harder which will increase their spin rate over time as well. In order to account for this we can turn to a simple calculation called Bauer Units.

Bauer units are a normalized version of spin rate that takes into account differing velocities across several different age groups. To calculate Bauer units for your pitches all you have to do is divide your spin rate by that pitch’s velocity. To give you a better idea for your average Bauer units, please see the table below. And although spin rate is definitely the more popular of the two, Bauer Units are what I would recommend you use to properly evaluate your pitcher’s performance.

Spin Axis/Direction (Tilt)

Great, now that we have a grasp on what effects spin rate has on each pitch, how can we further apply that to understand why pitches move the way they do? Enter Spin Axis/Direction (Tilt). This metric is the measure of the axis each pitch is spinning around depicted as either time on a clock or degrees. This measurement plays the single biggest role in defining the movement profiles of each pitch.

You may be confused at first because of the title of this section, our issue here is that several different companies have named the same measurement different things. At the end of the day, it doesn’t matter what you call it, we are going to consider them all the same thing for simplicity’s sake.

To go through an example of how this is calculated, imagine yourself behind a typical right-handed pitcher throwing his fastball. You’ll notice that each pitch tails slightly towards his arm side. This metric is the measure of exactly that. Looking at the graphic on the right here, you can see that once this pitch has been released it will be spinning back towards the pitcher’s hand at the angle depicted by the blue arrow. If we were to overlay a clock onto this pitch, you’d notice that it falls between the 12:00 o'clock and 1:00 o'clock mark. Exactly how far in between those two hour marks gives you our minute reading. This one is about at the halfway point between the two so it’d read with a spin axis at about 12:30.

So now that you have a good idea of HOW this metric is measured, what can we do with it? To be honest, a lot of things. Below you can see a chart that lists out the ideal spin axis readings for each pitch type for both lefties and righties. In the beginning, getting pitcher’s into these different ranges may be a good thing to do. To accomplish this you can work with different cues and grips. But once you have a better feel for it, or if you have the data to help back your decision making process here you can determine exactly what movement profile each pitcher’s pitches perform best at. But both of those topics are a discussion for a later day. For now, check out the ranges below and see where your guy’s stand.

Gyro Degree & Spin Efficiency

This is a pair of metrics that are a lot harder to understand if you are first diving into the pitch design realm. They are similar to the measurement we just discussed above, but the application of their effects on ball flight are completely different.

Starting with Gyro Degree. If you reference the images above, you’ll notice that spin rate is the 2D measurement of the way the ball is spinning from our perspective directly behind the pitcher. But this is an unrealistic metric to rely on solely because pitcher's will not always release the ball from straight behind it. Instead, we may see some variation of tilt forwards or backwards here. Gyro degree is simply a change in perspective from spin axis, rather than measuring from behind you can view this from above.

Take the animation to the left for example, you can picture the first pitch being released perfectly through the baseball - this would read as a 0° gyro degree. While the second was released slightly around the ball causing an increase in the pitch’s gyro degree - closer to a 45° gyro degree. A pitch with the highest gyro degree possible would be spinning around the third pitch’s axis with a 90° gryo degree and all of these numbers are simply flipped negatively for lefties.

As gyro degree gets closer to 90°, the amount of spin that aids in movement diminishes. And the percent of that spin being used in movement is called Spin Efficiency. These two metrics go hand in hand. The higher the gyro degree the lower the spin efficiency. Spin efficiency is displayed as a percent, and is used to determine the amount of useful spin (total spin * spin efficiency = useful spin) that will aid in a pitcher’s movement.

This metric is important because if you have a pitcher who has a high spin rate, but a low spin efficiency, they aren’t going to see the same success they should be seeing by pitching up in the zone. Gyro degree is the more specific metric to help us describe exactly what is going on, but spin efficiency helps paint a general picture of the whole story. Here is a link to a chart that describes the ideal spin efficiency and gyro degree for a number of different pitch types.

Horizontal & Vertical Break

All of the metrics we described previously go into displaying a measurement for how much each pitch is going to move and why. Our horizontal and vertical break numbers, often displayed as an xy plot, tell us exactly that. When glancing at this for the first time you may be confused how a pitch is technically “rising” 10 inches when it clearly is falling down due to gravity. Well that’s because this metric, and the chart you’re looking at, take gravity out of the equation.

The (0,0) mark on this chart doesn’t actually display a pitch that goes perfectly on a line from the pitcher’s hand to the catcher’s mitt - it shows us how a pitch would move with absolutely no spin falling with gravity (you can think of a knuckleball here). But as a pitcher puts spin on the baseball, through their spin rate and spin axis, you’ll begin to see that point on the chart move away from the center point. Simply put, this chart measures the amount of movement a pitcher creates when they release the ball.

The further away that pitch is from the center, the higher the spin rate it was. But not just our typical spin rate measurement, this is actually measuring how much useful spin is being applied to the ball to alter it’s pitch movement profile. A pitcher with a below average fastball spin rate may have a pitch with 8 inches of positive vertical break, while a pitcher with above average spin rate may have up to 20 inches.

Another important thing to note here is that most pieces of technology are going to provide you this information on a different scale. The break numbers on Trackman are going to be slightly different from those displayed on Rapsodo due to the way they are being tracked and calculated. That’s just something to keep in mind if you’re in a position where you will be evaluating player’s across several different pieces of technology.

The deviations from the axis here is a direct reflection of that pitch’s spin direction. If we were to impose a clock (like you see here), you will notice the astounding relationship between that pitch’s spin direction reading and where exactly it will end up on our plot.

Understanding how these metrics work together in order to create the best pitch arsenal for each of your guys is incredibly important, but even this measurement leaves out one important detail.


And that metric is of course velocity. Now, the current trend occurring at all levels of the game is the pursuit to simply throw harder. And while the average fastball velocity at the highest levels has steadily increased year after year, improving velocity is not the only way to manipulate this metric.

Before we jump into more on this though, I want to make sure you all understand that there is no shortcut to increasing velocity. It’s a process that takes time and ultimately is best improved by simply maturing if you’re a younger athlete. Once you’ve matured, the next step is to really work on hitting the weight room and doing mobility exercises to make sure you can put your body in the best shape it can be. Only then should you begin to look into different velocity training exercises such as weighted balls or throwing programs. Or as a good friend likes to say, “You can’t put the icing on a cake you haven’t baked”.

DISCLAIMER: ALWAYS CONTACT A PROFESSIONAL BEFORE PURSUING A VELOCITY PROGRAM. Your program should be specific to you, finding a one size fits all program online is a recipe for disaster.

Moving past that, increasing velocity is not the only way to use this metric to your advantage. Each pitch in a pitcher’s repertoire comes in at a different speed. The spread between those speeds can be the difference between a hitter picking it up and a swing and miss. To the right you’ll find a table with the ideal velocity differences by pitch type subtracted from a pitcher’s fastball velocity.

Wrapping It Up

Hopefully this article will serve you as a helpful reference on your journey through the pitch design process. If you are caught up by any of these metrics, I’ll provide links below to the in-depth breakdowns of each of them over on the YouTube channel. Understanding what the numbers mean is the first step towards making proper data driven player development decisions, so make sure you have this stuff down before you’re ever out on the mound with an athlete.

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