two seam fastball

A two-seam fastball is a pitch in baseball and a variant of the straight fastball.

The two-seam fastball is designed to have more movement that a four-seam fastball, and is a pitch to be used while the pitcher is ahead in the count, setting up an off-speed pitch or looking to get a strike out.

The pitcher grabs a baseball and finds the area on it where the seams are the closest together. Then, the baseball is rotated so that those seams are perpendicular to his body, with the index and middle fingers on each of those seams respectively.

Each finger should be touching the seam from the pads or tips to almost the ball of each finger. The thumb should rest underneath the ball in the middle of those two fingers, finding the apex of the horseshoe part of the seam. The thumb needs to rest on that seam from the side to the middle of its pad.

This ball will tend to move for the pitcher a little bit depending on velocity, arm slot angle and pressure points of the fingers.

This information is from Wikipedia.