There are two articles about the gyroball today, one in the New York Times and another by Yahoo! Sports' Jeff Passan.

Finally, the gyroball mystery solved (Yahoo)

The Japanese Gyroball Mystery (Old Grey Lady)

Some quotes:

Hearing this was like hearing Santa Claus doesn't exist. I had started my search for the gyroball nearly a year ago, when Daisuke Matsuzaka was introducing himself to the United States for the first time during the World Baseball Classic. Message boards postulated that he threw this mysterious pitch by using double-spin mechanics, which sounded more like car technology. The pitch was supposed to revolutionize baseball, and when I asked Matsuzaka whether he threw it, he said that he had accidentally and that he wanted to learn it. By the time the Boston Red Sox emptied a Brinks truck to sign Matsuzaka, the gyroball was a full-blown phenomenon.

Turns out everything we thought was wrong.

Well, almost everything.

Now I can say, without question, the gyroball is no myth.

...

And more:

If thrown correctly, Tezuka said, the two-seam gyroball should look to a batter like a slider and act like a fastball. That is why, as described in the title of the book he and Himeno wrote, it is a "miracle pitch."

Bonds was not convinced. In a highlight later on the DVD of Major League Baseball's 2000 tour to Japan, Bonds batted against Tetsuro Kawajiri. He looked at the video of him lunging for a pitch that seemed to have broken backdoor over the outside corner.

"That's a sidearm slider," Bonds said.

I asked whether it was a gyroball.

"I don't know what that is," he said.

What do y'all think?