Sinker (SI)

Definition

A sinker, also commonly referred to as a two-seam fastball, is a type of fastball that has either hard downward movement, strong arm-side movement or both, known for inducing ground balls.

The sinker or two-seamer is generally one of a pitcher's fastest pitches, although it doesn't have quite the same velocity as a four-seam fastball. The sinker is one of the most frequently thrown pitches in baseball, although its popularity has decreased in recent seasons. Sinkerballers are adept at limiting home runs.

A sinker is often a few ticks slower than a four-seam fastball, but it tends to have more movement. It drops more than a four-seam fastball -- hence the sinker name -- and is more likely to force grounders, where a four-seamer is more likely to generate swings and misses. Sinkers are often thrown with lower spin and lower in the strike zone than a four-seamer in an effort to keep the ball on the ground.

In addition to its vertical movement, a sinker moves in the same direction as whichever arm is being used to throw it (meaning a right-handed pitcher's sinker will break horizontally toward a right-handed hitter or away from a left-handed hitter). A sinker's horizontal movement might be described as "tail" or "arm-side run."

Grip

There are multiple grips that pitchers use to throw sinkers or two-seamers, 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, with the "horseshoe" of the baseball oriented vertically and one finger along each of the two seams.

If thrown with the same finger pressure, sinkers and four-seam fastballs can look similar. However, sinkers usually aren't thrown with the same finger pressure as a four-seamer. Finger pressure plays a large role in determining pitch movement.

Sinkers 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.

Origin

According to noted sabermetrician and writer Bill James, while the sinker existed before the 1950s, pitchers didn't explicitly try to throw it. They simply threw their fastballs -- and a select few of them had a sharp sinking movement on them. It is widely believed that around 1950, pitchers began to intentionally incorporate a wide range of movement on their fastballs. That's when the sinker finally came into its own.

In A Call

"sinkerball," "sinking fastball," "ground-ball pitch," "two-seamer," "running fastball," "tailing fastball"