Why all the Hype about the Gyroball Daisuke

Why all the Hype about the Gyroball? Daisuke Matsuzaka: Does he or doesn’t he? SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 2

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 SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 3

“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 SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 4

Seattle PI 10/18/06 Are these claims scientifically sound? Does anyone throw it? SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 5

The Science of a Baseball Trajectory 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. SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 6

The Science of a Baseball Trajectory The spin axis is the line connecting the south to north pole (“right-hand rule”) spin axis SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 7

The Science of a Baseball Trajectory Magnus force causes ball to break in direction that front edge of the ball is turning deflection Example: straight overhand fastball as viewed by batter— upward break opposing gravity spin axis rotation SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 8

More examples, as seen by batter deflection spin axis “ 12 -6” overhand CB: downward break deflection SABR 37, July 27, 2007 Alan M. Nathan overhand FB: upward break spin axis Page 9 Is the gyroball a miracle pitch?

More examples, as seen by batter Sidearm curveball by RPH breaks away from RHB 3/4 fastball by RHP breaks up and in to RHB SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 10

More examples, as seen by batter Note that spin axis is tilted a bit forward. cut fastball by RHP breaks up and away to RHB slider by RHP breaks down and away to RHB SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 11

Break (excluding gravity) of Matsuzaka’s Pitches (as seen by batter)--thanks to MLB Gameday ¾ FB 90 -95 mph 85 -90 mph 80 -85 mph Cut FB 75 -80 mph vertical break (inches) SFFB? CB/SLD horizontal break (inches) SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 12

Magnus force also depends on angle between spin axis and direction of motion. Largest when angle is close to 90 o: Zero when angle is 0 o: the gyroball side view “normal” pitch with sidespin Angle=90 o Maximum force SABR 37, July 27, 2007 Alan M. Nathan gyroball Angle=0 o Force=0 Is the gyroball a miracle pitch? Page 13

Courtesy, Ryutaro Himeno For pure gyroball, only force is gravity. • no sideways break • drops ~15” more than FB SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 14

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. SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 15

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 SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 16

from The New York Times: they got it exactly right! SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 17

Seattle PI 10/18/06 Pure nonsense! SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 18

Some additional thoughts l Gyroball thrown 85 -90 mph drops more than fastball ØSort of like a splitter, but even more drop l May look like slider to batter slider gyro Batter sees “red dot” and expects slider red dot identifies slider expects break to right “backup slider”—in former days, a mistake SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 19

Clip from Kazushi Tezuka’s Instructional DVD SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 20

Variation #1 If spin axis tilted slightly upward, ball breaks a little sideways: “gyroball with side force”. 15 o tilt gives ~4” break to side SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 21

Variation #2 If spin axis tilted slightly toward 3 B, ball breaks a little upward: “gyroball with lift force” 15 o tilt gives ~4” break up SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 22

Log of Matsuzaka’s Pitches (as seen by batter) 90 -95 mph 85 -90 mph 80 -85 mph 75 -80 mph Daisuke Matsuzaka: Does he or doesn’t he? several candidates SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 23

“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, 6/30/07 Nor can I SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 24

Is the Gyroball a Miracle Pitch? l We have come full circle ØGyroball does not have crazy trajectory people have claimed ØGyroball trajectory determined entirely by gravity ØTherefore, it seems like a useless pitch l But…. ØIf batter is expecting a typical fastball… ØIf batter misinterprets spin as a slider…. l My personal view: gyroball is a useful but not a miracle pitch SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 25

Thanks to …. l l l 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 So. SH for asking good questions Want to know more: • webusers. npl. uiuc. edu/~a-nathan/pob/gyro • a-nathan@uiuc. edu • Science and Baseball meeting, 4 PM today, DR 43 SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 26

spin s axis p i s SABR 37, July 27, 2007 Alan M. Nathan Is the gyroball a miracle pitch? Page 27