The Gyroball

In the months leading the MLB debut of former Japanese superstar Daisuke Matsuzaka with the Boston Red Sox in 2007, there was much written about a supposedly new pitch that he throws called the gyroball. A simple web search will result in lots of claims about the movement on this pitch. Below are links to some of the better stories about the pitch. Also included is my own description of what the pitch should do. The first link is a retrospective, published in October 2013.

Unspinning the Mythical Gyroball: The Demon Miricle Pitch That Wasn't Link to an article, authored by Barry Petchesky, that appeared in Deadspin on October 29, 2013. This is mainly old news, but it does summarize the current thinking about the mythical gyroball and hopefully puts the matter to rest for all time.

Physics of the Gyroball. My own brief description of the movement expected on a gyroball.

An Analysis of the Gyroball A paper co-written with ex-MLB pitcher Dr. Dave Baldwin and published in the 2008 issue of Baseball Research Journal, the offical publication of SABR.

Is the Gyroball a Miracle Pitch? Powerpoint slides of a talk I presented at the 2007 annual SABR convention.

Video-1 and Video-2: Some pretty nifty high-speed videos of some Japanese pitchers throwing the gyroball, using a specially marked ball to facilitate observation of the spin. Note particularly that the "+" on the front of the ball is barely moving as the ball rotates, indicating a "bullet"-type spin. Note also that the pitcher pronates the wrist (i.e., turns the palm to the outside) upon releasing the ball, much like a pitcher would do if throwing a screwball. However, the gyroball does not have the same spin as a screwball and should not be confused with it.

Technical paper co-authored by Dr. Ryutaro Himeno, the Japanese computer scientist who discovered the gyroball from elaborate computer simulations. The paper reports measurements of the movement of a gyroball pitched from a machine and interpretion in terms of lift and drag coefficients. Clearly this is a bit on the technical side.

Dr. Ryutaro Himeno, the inventor of the gyroball, has some very interesting stuff on his web site. Note particularly the very impressive high-speed movies, especially "movie 1" which clearly shows the spiral-type spin. The computer-generated movies are the results of very sophisticated computational fluid dynamics (known as CFD to aerodynamicists) using the Riken supercomputers. Such movies allow somewith with a trained eye to learn about the lift and the drag on the baseball.

The Gyroball Mystery , a PBS NewsHour Extra story by Adnaan Wasey.

Thrown for a Loop, the Dave Sheinin story in the Dec. 23, 2006 edition of the Washington Post.

Unwinding the Mystery of the Gyroball, the Brett Bull story that first appeared on Jan. 26, 2007 at

Image courtesy of New York Times
The Japanese Gyroball Mystery, the Lee Jenkins story in the Feb. 22, 2007 edition of The New York Times. Take particular note of the graphic shown here. If you understand this graphic, then you understand a lot about the gyroball.

Finally, the gyroball mystery solved , the Jeff Passan story which first appeared at on Feb. 22, 2007.

Chasing the Demon Sphere , the Patrick Hruby story which first appeared on Feb. 23, 2007 at After reading the article, you might also want to hear a 30-minute podcast of Patrick's interview with Will Carroll of Baseball Prospectus.

Podcast interview of ex-MLB pitcher Dr. Dave Baldwin by Scientific American writer Steve Mirsky on the April 4, 2007 Science Talk. The interview covers a wide range of interesting topice in baseball science, including the gyroball. As a former pitcher and a scientist, Dave brings a unique perspective to this discussion.

Podcast interview that I did with, principally about the gyroball and about a few other things also. See also a blog based on this interview.

The Secret of the Miracle Pitch. A link to, the Japanese version of The book is co-authored by Japanese pitching coach Kazushi Tezuka and Ryutaro Himeno. But beware: the book is in Japanese. Nevertheless it has great pictures that are good in any language. A steal at 2100 Yen! The cover of the book is shown below.