NPR News

The Knuckleball: A Confounding Baseball Mystery

NPR | By Uri Berliner

Published February 28, 2008 at 4:47 PM EST

No pitch is shrouded in as much mystery and mythology as the knuckleball.

It starts with a misnomer. The knuckleball isn't thrown with the knuckles. Yes, a pitcher named Eddie Cicotte came to the major leagues 100 years ago tossing a baffling pitch that he gripped with his knuckles. And, yes, that's the story of how the knuckleball got its name.

But over the years, it has become the norm for knuckleball pitchers to hold the ball with their fingertips, not their knuckles. Either way, the goal is the same: to keep the rotational spin on the ball to a minimum. When the ball doesn't spin much, its trajectory is affected by air currents. In other words, it moves very erratically.

The position of the seams as the ball slowly rotates through the air is crucial. Here's how the pitch's movement is explained by Porter Johnson, a physics professor, writing in Scientific American:

For a knuckleball, the important thing is that the ball rotate about an axis so that the seams are on one side of the front of the ball at one instant, whereas a little later they are on the other side of the front of the ball. The ball will then drift in the direction of the leading seam, and then drift back when the seam becomes exposed on the other side.

The result of all this drift can be sheer hell on hitters — and catchers. The verbs commonly used to describe what a knuckleball does are flutter, dance and dart. The knuckleball sometimes appears to move from side to side.

Batters have plenty of time to size up a knuckleball because it is thrown at a relatively leisurely speed — maybe 20 to 30 mph slower than the typical fastball.

But the unpredictable movement of the knuckleball confounds even the best hitters. Some major leaguers get frustrated that such a slow pitch can be so devilishly hard to hit. Others accept the mystery of the knuckleball fatalistically.

"I never worry about it," said former all-star first baseman Dick Allen. "I just take my three swings and go sit on the bench. I'm afraid if I ever think about hitting it, I'll mess up my swing for life."

So why don't more pitchers become knuckleballers? The knuckleball comes with its own set of problems. For catchers, it can be a nightmare. For the same reason the pitch is difficult to hit, it's difficult to catch. Catchers use a bigger mitt when handling a knuckleball pitcher. Base runners find it relatively easy to steal when a knuckleballer is on the mound because the pitch travels slowly and gets past the catcher more frequently than it does when other pitchers are on the mound.

Finally, the knuckleball is a difficult pitch to master. Finding the right grip and learning how to control the rotation of the ball are critical. If the knuckleball doesn't spin at all — or if it spins too much — the odds of success tilt toward the batter. He'll stand in and see the ball coming in slow and straight. And that's when he'll hit it hard and deep and finally get the best of the mysterious knuckleball.