Baseball Knuckle-Curve (KC)

Baseball Knuckle Curve

A knuckle-curve is a pitch in baseball that is exactly as its name implies: a combination between a knuckleball and a curveball. And while the naming of the pitch is as simple as it gets, the pitch itself is something of a mystery in modern baseball. Keep reading to learn how knuckle-curves work in baseball.


 Knuckle-curves behave simultaneously like a knuckleball and a curveball. A knuckleball is a pitch that is notable for its complete lack of spin, giving it unpredictable and seemingly random movement upon release. A curveball, on the other hand, is a pitch that is completely reliant on its spin. A curveball generates enough spin that the ball breaks downward on its way to home plate. As such, the knuckle-curve is something of a contradiction of terms, but some pitchers have mastered the fine art of combining the two pitches.

The knuckle-curve is a pitch that is a combination between a knuckleball and a curveball. This means that the pitch ideally features the downward movement of a curveball while maintaining the lack of spin that one gets from a knuckleball. Seeing as these two pitches are such a contradiction to combine, the knuckle-curve is more of a spectrum.

Some pitchers will have more spin on the pitch, more closely resembling a curveball, while others will throw the pitch with less spin, more similar to a knuckleball. Seeing as there’s no exact science to throwing a knuckle-curve, it’s one of the most difficult pitches to throw in all of baseball. Being a combination of two of the more difficult pitches to hit in the sport, making good contact with a knuckle-curve as a batter is a tall order.

How to Throw a Knuckle-Curve

Being such a rare and strange pitch, there’s no truly established way to throw a knuckle-curve. The most common way to throw a knuckle-curve is to use a knuckleball grip and snap the wrist the same way that one does with a curveball. Throwing a knuckle-curve is no exact science, so pitchers have to work the pitch out by feel.

Eventually, something will “click,” and a knuckle-curve will be within reach. Until then, it’s important to keep experimenting until the pitch works. It’s also important to remember that the knuckle-curve is a spectrum, so your version might have more or less spin and movement than others.


The knuckle-curve is officially a variation of both the knuckleball and the curveball, so there are no official variations on a knuckle-curve because it is such an unusual pitch in and of itself. However, there are some variations on a knuckleball that are similar to a knuckle-curve.

One of these is knuckle-slider, which is similar to a knuckle-curve in that it has a low spin rate, but instead of moving downward, it moves side-to-side like a slider. Similarly, there are plenty of variations of the curveball in baseball which break in different directions compared to the usual 12-6 curveball (straight up and down). As far as the knuckle-curve goes, though, it stands entirely on its own.

History of the Knuckle-Curve

The knuckle-curve, as it is known today, was invented by Dave Stenhouse in the 1960s. Stenhouse was always a knuckleball pitcher, but when he arrived in the major leagues, he realized his knuckleball could be used as a breaking pitch, and thus, the knuckle-curve was born.

Since then, the pitch has been extremely rare, as it’s so difficult to master. The most notable users of the knuckle-curve since Stenhouse have been Jesse Haines, Freddie Fitzsimmons, and Hoyt Wilhelm. However, the pitch is almost never seen in the MLB today.

Best Knuckle-Curve Pitchers

  • Jesse Haines
  • Freddie Fitzsimmons
  • Hoyt Wilhelm


What is a knuckle-curve in baseball?

In baseball, a knuckle-curve is a combination of a standard curveball and a knuckleball. It is an exceedingly rare pitch in baseball today, as it’s so difficult to master. The pitch, when thrown correctly, has the ability to break downwards like a curveball but also the same lack of spin as a knuckleball. The absence of spin makes the ball flutter unpredictably through the air on its way to home plate. The knuckle-curve is similar to a knuckle-slider.

How is the knuckle-curve thrown in baseball?

While there’s no exact science to throwing a knuckle-curve, it’s most commonly thrown by using a knuckleball grip in conjunction with the same wrist-snapping motion that’s used to throw a standard curveball. Throwing a knuckle-curve can take quite a long time to master, and some professional pitchers only master the pitch after many years. When learning how to throw a knuckle-curve, it’s important to be open to experimentation in order to find out what works for you.