There are different types of fastballs, but the four-seam fastball is the most common. To throw a four-seam fastball, place your index and middle fingers across the seams on top of the baseball. Place your thumb across the seams on the bottom. Grip the baseball loosely, and release.Continue Reading
Position your index and middle fingers across the seams on top of the baseball. Leave about half an inch of a gap between each finger. Place your thumb across the seams underneath the baseball.
Grip the ball loosely as you would if you were holding an egg in your fingertips. Leave a little bit of space between your palm and the baseball.
Let your fingers roll off the fastball as you release it. Keep the friction between your hand and the baseball to a minimum for a higher velocity.