Spin Rate, Spin Axis & Gyro Spin - Part 2


In Part 1 we talked about spin rate and how it affects fastballs.  Part 2 will cover spin axis and tunneling fastballs and offspeed.

Spin Axis and Gyro Spin

There are few pitches thrown in baseball that are perfectly straight.  Typically guys are said to have natural “run” movement towards the arm side or “cut” movement towards the glove side.  This is because very few people have true backspin on the baseball. The angle or tilt of the baseball will alter the way that it moves.  This angle or tilt is typically referred to as the spin axis.

While fastballs can be altered by changing the axis, breaking balls are even more susceptible to change in this way.  For example a true overhand curveball would ideally be thrown perfect topspin, a 12 o’clock axis. As it reaches home plate it would work straight down (like a shadow hitting the 12 and the 6 on a clock) giving it a significant amount of vertical break and very little horizontal break.  However, if the spin axis was closer to 11:00, the pitch would still have significant vertical break, but also more horizontal break. One is not necessarily better than the other, however knowing which spin your pitch has is important. While the spin rate of a breaking pitch is important it works differently than a fastball because not all spin is equal.

There is another factor that goes along with spin axis - gyro spin.  Everyone has heard of the famous gyro ball that was said to be the secret weapon of Daisuke Matsuzaka.  Gyro spin is similar the spiral of a football.  It allows the ball to resist drag but also keeps the ball straight.  Therefore a gyro ball would spin like a football and stay straight (also known as a bad slider).  The amount of gyro spin on each pitch will factor into the overall effectiveness of the pitch. With the exception of sliders, the less gyro spin the better as this spin does not help the pitch break.  As I said earlier, not all spin is created equal. Rapsodo provides a number for the total spin minus the gyro spin on each pitch, also known as useful spin. The ball will typically break more if there is less gyro spin, or more true spin driving the break of the pitch.   

While it may be difficult to drastically improve the spin rate of a pitch in a short amount of time, the spin axis can often be changed simply by tinkering with grip and the feel at release.  Knowing the spin axis and useful spin also takes the guesswork out of improving a pitch because it will provide instant feedback of if it improved. While much of it is still trial and error, it can even be beneficial just to know what the ball is really doing, not just what the eye test tells us.  The classic, “get on top of it” is not always the answer. We often see that some guys are really just trying too hard to get a certain break. Some guys have struggled with curveballs for years that were really trying to force a slider, with an axis around 3:00 and low spin efficiency to break straight down.  Breaking balls can be much easier to duplicate if you aren’t fighting them the whole time and the overall command can improve drastically.