Post by Brian McAfee
Do you ever wonder why some pitchers in the MLB seem to consistently blow elevated, 88 mph fastballs by hitters? Those fastballs probably have elite vertical movement. Let me explain.
Quick Background on Movement and Spin
Imagine a four-seam fastball flying towards the plate. As gravity causes the ball to drop, the backspin from the seams generates lift (vertical movement). Faster spin paired with a more efficient axis of rotation creates a stronger lift force and will result in more vertical movement. Now imagine Pitcher A and Pitcher B. Pitcher A throws a four-seam 88 mph and has an extremely high spin rate and spin efficiency (meaning his fastball has high useful spin). Pitcher B throws his four-seam 88 mph and has an average spin rate and efficiency. If all other factors were held equal, I would put all my money on Pitcher B getting hit significantly harder than Pitcher A.
Early in my college career, I was Pitcher B. I had three other decent off-speed pitches to play off my fastball, and so I got away with this mediocre fastball against weaker hitters. I knew I needed either more velocity or more movement though. Without any knowledge of my spin rate or efficiency, I decided my lower arm slot would translate to a good two-seam fastball. Looking back on my career, this was the single most important discovery I made. If I had a Rapsodo to work with, developing this pitch would have been much easier. Instead of guessing how much run or sink each new grip had, it would have given be an exact number.
Although the true variables that influence fastball spin rate at given velocities aren’t known (besides juicing your fingers up with pine tar), knowing your strengths and weaknesses as a pitcher will allow you to develop a plan to improve your strategy to attack hitters. By playing around with different arm slots and grips and learning how your pitches move, you can quantify your progress in terms other than velocity. If you happen to develop a fastball with elite horizontal or vertical movement, this is a huge selling point for college coaches that know what they’re looking for. In professional baseball, this is a major factor in deciding if you have enough potential to pitch successfully in higher leagues. Here’s a quick snapshot of Trackman data from an MLB front office analytics report:
The breakdown of pitch type with movement and velocity gives them a good idea of how successful these pitches would be, outside of their location and sequencing. Pitching ultimately boils down to fooling the hitter. Yes, you’ll need to “pound the zone”, “command the fastball”, and all of the other traditional phrases you’ll hear, but what happens when the hitter picks up the pitch and starts his swing? Very simply put, he predicts where he thinks the ball will end up and tries to swing his bat to that spot. If you constantly generate soft contact, this means the hitter is being fooled. If you constantly generate swings and misses, he’s even more fooled. How can you fool the hitter? At a lower level, velocity usually works. As hitters’ swings get quicker and they can wait longer to recognize the spin on the pitch, this doesn’t work quite as well, although it is still an enormous contributor to success. Spin rate and spin efficiency are two of the main factors that cause a movement on a pitch. That 88 mph fastball with elite vertical movement? It ends up much higher than the hitter would expect, and he swings under it. Your ability to continue to climb the ranks of baseball will be determined by fooling hitters and generating these swings and misses. Say what you want about working efficiently (because it does generate value), but strikeouts show dominance. And dominance will allow you to keep playing.
Using the Rapsodo to Reach Your Full Potential
The Rapsodo uses optical tracking technology to pick up the spin of the baseball while it travels towards the plate. Here is a screenshot of the data given:
I’ll briefly breakdown what each of these mean, as explained by the Rapsodo website, and what you should be looking for on each pitch.
Along with these metrics, the Rapsodo provides accurate strike zone analysis, total inches of vertical and horizontal break, and the 3D trajectory of the pitch. Before getting into a couple different pitches and what to look for, this visual gives a good representation of the three axis of spin. Driveline Baseball has some excellent resources that go more in-depth on the physics side. All you need to remember is that useful/true spin is also referred to as traverse spin, and is perpendicular to the direction of travel. In the figure above, this would be rotation around the X-axis or Z-axis. This transverse spin contributes to movement, which is why it is called useful spin. Rotation around the Y-axis is known as gyroscopic spin, and doesn’t contribute to movement (imagine the spiral of a football).
Since the objective is generally to create as much movement as possible, a higher spin rate is better. The more useful spin (spin efficiency closer to 100%), the more the spin will translate to break. At a lower arm slot, the ball might rotate more around the Z-axis and create horizontal break. According to the Rapsodo website, the MLB average is 69.8% with 2,308 total rpm. Rick Porcello averages 92.8% and Masahiro Tanaka averages 65.6%. Play around with different grips and quantify what works best for you.
Depth is usually good, so lower spin efficiency creates some depth by eliminating lift. Having a higher total spin rate creates potential for sharp, horizontal break. The MLB average is 38.9% with 2,090 rpm. There are numerous different types of sliders at high and low spin rates, so it’s all about finding what works best for your arm slot, hand size, repertoire, etc.
As mentioned above, having lots of vertical movement is great. But also, having a lack of vertical movement can be effective as well. Falling in the middle of these two extremes without run or cut is where you can get into trouble. Recognize how your fastball moves and your potential to develop different types of fastballs to use based on how the hitter is swinging. For example, I would throw primarily two-seam fastballs the first two times around a lineup. Once the hitters gradually adjust (or if I’m looking for fly balls), I would switch to four-seam fastballs. Recognize the hitter’s approach, the situation, and get comfortable with different grips.
In conclusion, there are many complexities that determine how individual pitchers spin pitches. It all comes down to physics, but with such a high-speed event and numerous variables, it makes it challenging to understand. If getting a Mariano Rivera cutter were as simple as mimicking his grip and throwing it 94 mph, baseball wouldn’t be fun. It often takes years to perfect your repertoire of pitches. By practicing around during catch play, it helps build that muscle memory necessary for developing feel. But to truly master a new pitch, it might take a little more than eyeballing how something moves. The Rapsodo gives you that quantitative edge to discover your strengths and weaknesses and guides you in the right direction to develop feel and elite movement.