The gyroball is a pitch that was invented by Japanese pitching coach Kazushi Tezuka with the help of computer scientist Ryutaro Himeno, who determined its properties through elaborate simulations, in a book published in 2001 entitled Makyuu no Shoutai ("The Secret of the Demon Miracle Pitch").
Its trajectory lies somewhere between a fastball and a curve, i.e. it falls faster than a fastball, but slower than a curve, and hardly breaks inside or outside. It achieves this unusual effect because it spins on an axis parallel to its trajectory, somewhat akin to a football being thrown with a perfect spiral. A gyroball must be thrown sidearm or with a lower than three-quarters arm angle, with the thumb and index fingers imprinting the unusual rotation at the point of release.
A lot of misinformation has circulated about this pitch, with claims that it breaks as much as three feet when reaching home plate. The myth surrounding the pitch seems to be an integral part of its effectiveness, as batters are unsure what to be on the look-out for. Japanese star Daisuke Matsuzaka has used this to his advantage, remaining coy about whether or not the pitch is part of his repertoire, although evidence suggests that he did not use it in his rookie season with the Boston Red Sox.