What it is

Spin Efficiency is the percentage of Total Spin that contributes to creating Movement on a pitch. The higher the percentage, the more the ball will move up, down, left or right. Only Backspin, Topspin and Sidespin create force on the ball to make it move up. Riflespin, also known as gyro spin, creates no lifting force on the ball and reduces Spin Efficiency. Pitches with a high Spin Efficiency are sometimes described as spinning true or clean. Pitches with a low Spin Efficiency are sometimes described as spinning off axis or tilted.

Why it matters

The higher the Spin Efficiency, the more movement on the pitch. Higher Spin Efficiency also tends to create more velocity on a four-seam fastball. If the ball has only Riflespin, which spirals like a football or bullet, there is no Movement on the ball from the batter’s viewpoint. This pitch would have 0% Spin Efficiency. The higher the Spin Efficiency, the more movement on the pitch. Higher Spin Efficiency also tends to create more velocity on a four-seam fastball.

How it is used

When working on a four-seam fastball, increasing Spin Efficiency is a common priority. This creates more Movement in the direction of the Arm Slot. Players with high Arm Slots will create more ride, and players with low Arm Slots will see more arm side run. Keeping your hand “behind the ball” all the way through the release will improve both Spin Efficiency and Speed. Generally, aligning the Spin Direction with the Arm Slot will result in higher Spin Efficiency. The Last Touch point on the 3D Clockface can also help you visualize where the fingers are coming off the ball. Coming off the side of the ball will increase Riflespin and reduce Spin Efficiency. This is often referred to as “cutting” the fastball. 

With breaking balls, there can be a tradeoff between Speed and Spin Efficiency. This is why curveballs, which tend to have a higher Spin Efficiency, tend to have a lower Speed than sliders, which have a lower Spin Efficiency and higher Speed. Getting “over the top” or “around” the ball on a curveball tends to create a higher Spin Efficiency and more Movement but can also reduce the pitch’s Speed.