A pitcher can do anything and everything before and during his delivery to prepare himself to throw the best pitch he is capable of. At the very moment he releases the ball, all he can do is hope it misses a barrel. Other than funky deliveries and peculiar body shapes, what contributes to the effectiveness and deception of the pitch? Once the ball leaves the pitcher’s hand physics takes over and the ball begins to spin.
Every pitch’s spin rate can be precisely quantified by determining how many times the ball rotates around its axis. The measurement for this is labeled as revolutions per minute (RPM) or magnitude. Many outside factors such as gravity, drag force and magnus force affect the RPMs of a pitch. Gravity effectively forces the ball in a downward motion once the ball is in flight. Drag is an aerodynamic force that occurs in all objects in motion. The fastest a pitch will ever travel is when it is first released from the pitcher’s hand. That point of peak velocity is known as muzzle velocity. From there, outside forces act upon the ball while the ball pushes the air out of its path incrementally decreasing the velocity of the ball. This process is known as drag. It is essentially the aligned and opposing air that retards the velocity of the pitch. The shape, size and velocity of the ball, as well as the density and viscosity of the air affect drag force. Magnus Force is present on all spinning pitches and is responsible for the break, curve, and trajectory of the ball. For example, a traditional four-seam fastball thrown with true backspin will have an upward pushing magnus force (opposing the downward forces of gravity) thereby delaying the effect of gravity. We will look more into magnus force as we progress through the article.
Why Should You Care about Spin Rate?
Outside of raw velocity, spin may be the most significant consideration when developing your identity as a pitcher. I’m a big fan of power pitching and the excitement that velocity brings to the table, but fastball velocity may not always be the biggest contributing factor to getting outs. You may be asking yourself if spin rate is a contributing factor to velocity and the answer is no. Spin rate acts independent of velocity development, yet is heavily dependent on fastball velocity, which you can see in MLB’s very own 2015 Statcast chart below.