The four-seam fastball is probably the most thrown pitch in baseball and the easiest to control. Four-seamers rely heavily on Speed and location but can benefit from Movement as well. Four-seam fastballs generally create more Vertical Movement than other fastball types, particularly for high Arm Slots.

The four-seam fastball is gripped across the horseshoe so that the ball rotates with four different sections of the seam crossing through the path of rotation.

A typical four-seam fastball has a Spin Direction that’s near or slightly above your Arm Slot. Spin Efficiency is usually high – think 90-100%. Some pitchers are able to create more separation between Spin Direction and Arm Slot without sacrificing Spin Efficiency. This can be particularly effective.

Four-seam fastballs can benefit if you are able to generate a high Spin Rate, especially if you have a higher Arm Slot and can create a lot of Vertical Movement. 23 to 24 times your Speed is generally an average Spin Rate (for example 1900 RPM would be fairly average at 80 MPH, but 1400 would be more typical at 60 MPH).

Four-seamers are often most effective high in the strike zone. Use the STUFFpL heatmap to see where your four-seam fastball would perform best.

The two-seam fastball is a type of fastball that generally creates more Arm-Side Horizontal Movement and less Vertical Movement. Two-seam fastballs are sometimes referred to as sinkers.

The two-seam fastball is gripped in the same direction as the horseshoe so that the ball rotates with two different sections of the seam crossing through the path of rotation.

Like a four-seam fastball, a two-seamer usually has a Spin Direction that’s near your Arm Slot. Spin Efficiency is often a little lower – think 80-90%.

Generally, Spin Rate doesn’t have as big of an impact on two-seam fastball performance, but for reference an average Spin Rate for two-seam fastballs is around 23 times your Speed.

Pitchers with lower Arm Slots, lower Spin Efficiencies, and/or lower Spin Rates may find that a two-seam fastball is a better fit than a four-seam fastball.

Two-seamers are often most effective low in the strike zone, where they often cause batters to hit ground balls. Use the STUFFpL heatmap to see where your two-seam fastball would perform best.

A cutter or cut fastball is thrown similarly to a four-seam fastball, but with a lower Spin Efficiency and more separation between the Spin Direction (blue arrow) and Arm Slot (yellow arrow).

Cutters can produce glove-side Horizontal Movement for pitchers with an overhand Arm Slot, unlike other fastballs which usually produce arm-side Horizontal Movement. With a lower Arm Slot, cutters may produce a mostly vertical shape.

Cutters are generally somewhat slower than other fastballs and have less overall Movement.

Some pitchers use a cutter as their primary fastball, while others use it as a secondary pitch. The shape of a cutter is somewhere between a four-seam fastball and a slider. It may sometimes be classified as a breaking ball instead of a fastball.

Cutters are often most effective high in the strike zone.