A two-seam fastball is generally one of a pitcher's fastest pitches, although it doesn't have quite the same velocity as a four-seam fastball. A two-seam fastball is one of the most frequently thrown pitches in baseball.
A two-seam fastball is often a few ticks slower than a four-seam fastball, but it tends to have more movement. With a two-seamer, the ball moves in the same direction as whichever arm is being used to throw it (meaning a right-handed pitcher gets rightward movement on a two-seamer).
There are a variety of grips that pitchers use to throw two-seam fastballs, but the most common occurs when the pitcher puts his two fingers directly on top of the part of the ball where the seams are closest together.
If thrown with the same finger pressure, two-seam and four-seam fastballs can look similar. However, two-seam fastballs usually aren't thrown with the same finger pressure as a four-seamer. Finger pressure plays a large role in determining pitch movement.
Two-seam fastballs are especially useful for pitchers who lack the raw velocity to overpower hitters. The movement and deception on the pitch, coupled with its speed, can often make up for that slight dip in velocity.
Watch: John Smoltz demonstrates how to throw a two-seam sinking fastball.
In A Call
"two-seamer," "moving fastball," "running fastball"