Page 1 SABR37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Is the Gyroball a Miracle Pitch? Alan M. Nathan University of Illinois at

Page 2SABR37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch?

Why all the Hype about the Gyroball?

Daisuke Matsuzaka:Does he or doesn’t he?


Secret of the Demon Pitch by Kazushi Tezuka and Ryutaro Himeno

Tezuka: pitching coach who “invented” the pitch. He also has an instructional DV

Himeno: computer scientist who discovered its properties with elaborate simulations


“It's quickly becoming the Bigfoot of baseball, an urban legend born in a Japanese lab and racing across the Internet. They call it the "gyroball"—the exact translation is probably closer to "Demon Sphere Gyro Ball"—and it's either the first new pitch in nearly four decades, or a complete and total sham.”—Popular Mechanics, 11/06


Seattle PI

10/18/06

Are these claims scientifically sound?

Does anyone throw it?


The trajectory of a pitched baseball in flight is governed by the gravitational force and the Magnus force on a spinning baseball.

Gravity makes the ball drop by 3-4 ft, depending on speed

The Magnus force deflects the ball by an amount that depends on the spin (rpm), the speed, and the orientation of the spin axis.

The Science of a Baseball Trajectory


The spin axis is the line connecting the south to north pole (“right-hand rule”)


spin axis


Magnus force causes ball to break in direction that front edge of the ball is turning

spin axis

deflection

rotation

Example: straight overhand fastball as viewed by batter—upward break opposing gravity



More examples, as seen by batter

spin axis

“12-6” overhand CB:

downward break

overhand FB:upward break

spin axis

deflection

deflection

spin axis


Sidearm curveball by RPH

breaks away from RHB

More examples, as seen by batter

3/4 fastball by RHP

breaks up and in to RHB


More examples, as seen by batterNote that spin axis is tilted a bit forward.

slider by RHP

breaks down and away to RHB

cut fastball by RHP

breaks up and away to RHB


90-95 mph

85-90 mph

80-85 mph

75-80 mph

Break (excluding gravity) of Matsuzaka’s Pitches

(as seen by batter)--thanks to MLB Gameday

horizontal break (inches)

vertical break

(inches)

¾ FB

CB/SLD

Cut FB

SFFB?


Magnus force also depends on angle between spin axis and direction of motion.

Largest when angle is close to 90o:

Zero when angle is 0o: the gyroball

side view

“normal” pitch with sidespin

Angle=90o

Maximum force

gyroball

Angle=0o

Force=0


Courtesy, Ryutaro Himeno

For pure gyroball, only force is gravity.

• no sideways break

• drops ~15” more than FB


An aside for physics geeks….

When spin axis of a spherical ball coincides with the direction of motion, there is complete symmetry about that direction. So, the ball has no way of “knowing” which way to break. Therefore, there can be no break.


Is this all “theoretical”?

Proceedings of the Asia-Pacific Congress on Sports Technology,

Tokyo, 2005

Translation: Magnus force = 0 for gyroball…exactly as expected theoretically


from The New York Times: they got it exactly right!


Seattle PI

10/18/06

Pure nonsense!


Some additional thoughts Gyroball thrown 85-90 mph drops more

than fastballSort of like a splitter, but even more drop

May look like slider to batter

Batter sees “red dot” and expects slider

red dot identifies slider

expects break to right

“backup slider”—in former days, a mistake

slider gyro


Clip from Kazushi Tezuka’s Instructional DVD


If spin axis tilted slightly upward, ball breaks a little sideways: “gyroball with side force”.

Variation #1

15o tilt gives ~4” break to side


If spin axis tilted slightly toward 3B, ball breaks a little upward: “gyroball with lift force”

Variation #2

15o tilt gives ~4” break up


90-95 mph

85-90 mph

80-85 mph

75-80 mph

Log of Matsuzaka’s Pitches(as seen by batter)

Daisuke Matsuzaka:Does he or doesn’t he?

several candidates


“While (Ranger’s lefty reliever C. J. ) Wilson said he threw the pitch against both Alex Cora and Kevin Youkilis in the eighth inning of a May 26 game between the Sox and Rangers, neither batter could verify the claim.”

Manchester Union Leader, 6/30/07pfz vs pfx

0.00

2.00

4.00

6.00

8.00

10.00

12.00

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00

pfx

pfz

all pitches

Cora or Youkilis

Nor can I


Is the Gyroball a Miracle Pitch?

We have come full circleGyroball does not have crazy trajectory

people have claimedGyroball trajectory determined entirely by

gravityTherefore, it seems like a useless pitch

But….If batter is expecting a typical fastball…If batter misinterprets spin as a slider….

My personal view: gyroball is a useful but not a miracle pitch


Thanks to …. R. Himeno for sharing his diagrams Dave Baldwin for teaching me about the craft

of pitching Will Carroll (BP) for some helpful

conversations Dan Fox (BP) for providing the Gameday pitch

logs for Matsuzaka The bloggers at SoSH for asking good

questionsWant to know more: • webusers.npl.uiuc.edu/~a-nathan/pob/gyro• [email protected]• Science and Baseball meeting, 4 PM today, DR43


spis

spin axis

Documents

Page 1 SABR37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Is the Gyroball a Miracle Pitch? Alan M. Nathan University of Illinois at