Knuckleball Pitcher Wright Has Knee Surgery; Physics of Pitching; Stephen Darst, Has-Been Knuckleballer at 13

Last month, Red Sox pitcher Steven Wright had to sit out the World Series (the Sox won) because his left knee was acting up again. MassLive reported that on November 12 he “underwent a left knee arthroscopy and debridement…at the Hospital for Special Surgery in New York. Dr. Riley Williams performed the procedure.”

The Red Sox expect Wright to return to pitching in the 2019 season after the knee has been rehabilitated.

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Popular Science (in its October 4 issue), physicists like Alan Nathan and Eric Goff, and baseball’s Trevor Bauer (pictured) are all studying the physics of the baseball pitch. Bauer applies the knowledge when improving his pitches and developing new ones.

In order to get baseballs to drop and curve across the plate, pitchers manipulate their grip and timing. While most pitchers don’t think about the physics of their pitches, Bauer says, it’s the way the air moves around the rotating baseball that gets those strikeouts. While others are implementing complex fluid dynamics unintentionally, Bauer studies it to figure out how to add new pitches to his quiver. During the break between the 2017 and 2018 seasons, Bauer was able to scientifically develop a slider he never had before. And to do so, he had to understand what really goes into a pitch.

“There are a lot of tools that the pitcher has at his disposal,” Alan Nathan, a retired physicist at the University of Illinois who studies the physics of baseball. “I think the primary things that play a role are the speed, the spin rate, and the spin axis.”

The pitch is all about air flow, but sometimes “it can be a lack of flow that makes a pitch valuable.” Meaning lack of spin, as in the knuckleball.

Airflow across the baseball can move in smooth sheets called laminar flow, or turbulent pockets. The difference in flow is created by how the seams turn into the air and impact how the ball will move, says Bauer.

Pockets of turbulent air are what create the knuckleball. “A really well thrown knuckleball in baseball might tumble about a half to a full turn on the way to the plate,” Goff says. This lack of spin removes the Magnus force from effect, and leaves the combination of laminar and turbulent flow as the seams of the baseball catch the air. This creates a pitch that bobs and weaves as small changes cause turbulent flow in different places around the ball, pulling it through the air unpredictably.

“The erratic movement on a knuckleball is an example of what physicists call a chaotic function,” Nathan says. “A small little change ijn those release conditions could make a really big change in what happens to the ball.” Accidentally putting spin on one creates a big slow pitch for a hitter. Throwing one is like squeezing a watermelon seed out of your fingers in an attempt to put as little spin on the ball as possible, says Goff.

After learning about how Bauer worked with his dad to craft his new slider, we’re curious to see how they’d go about fashioning the perfect knuckleball. That’s a tough one.

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A prodigy of yesteryear we’re just hearing about is Stephen Darst, who in 1967 published a brief memoir in Sports Illustrated about “The Short, Happy Life of a Knuckle-ball Pitcher.”

As a juvenile athlete I was not an absolute idiot, perhaps, but certainly far from gifted in almost every department of sport. However, when it came to throwing a knuckle ball at a bewildered batter I was a 10-year-old prodigy.

I developed the art while playing catch with my brother….

I had experimented with all the known grips and twists, trying to get some variety in my pitching, but nothing worked until my brother came home one fine day with a working knowledge of the procedures for throwing a knuckle ball. The trick, for players of less than full maturity, was to grip the ball normally with the ring and little fingers and thumb, doubling up only the first and second fingers.

But then disaster struck. Darst’s knuckleball was good enough to confound pre-teen batters, but 13-year-old batters were another matter.

During all that time I pitched at least four no-hitters, and the Brother Spitz team went unbeaten. Then just at the point when my athletic future looked brightest disaster struck. It hit right smack in the fourth inning of a scoreless game in the middle of my 13th year. I threw my best knuckler to the lead-off batter and followed its journey to the catcher’s glove, like a father watching a child dart across a street through traffic. I waited for that climactic instant when my pitch would duck safely under the menacing bat. It ducked, but so did the bat….

And that was that: “Kids of 13, I suddenly discovered on the mound that day, could follow a curve, wait for the break, pick up the flight and hit the ball horrifying distances. The knuckleballer of 12 had lost his magic.”

It’s not so easy for batters of any age to hit a knuckleball, even if they get used to seeing it. So we wonder: How much of a true knuckleball was Darst throwing during his three and a half glory years of stellar pitching? Did he really have to retire at age 13? Perhaps he could have refined his technique with a little tutoring.



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