We have been pitching baseballs on this patch of earth known as America for more than a century and a half, and by now we thought we had exhausted the possible combinations of spins and arm angles that create the known spectrum of standard pitches and their offshoots. Fastballs have backspin. Breaking balls have topspin. For a changeup, reduce the spin. And so on and so forth. There hasn't been a truly new pitch introduced into this catechism since the split-finger arrived in the early 1970s.

But when Japanese import Daisuke Matsuzaka takes the mound for the Red Sox this season, a large community of international baseball connoisseurs, message board mavens and various other historians, fanatics and believers (though, tellingly, few folks within Major League Baseball itself) will be watching closely to witness the dawn of a new pitch: the mysterious, and quite possibly mythical, gyroball.

The gyroball's purported debut in America has all the hallmarks of a Japanese movie monster, from the pitch's birth in a scientist's laboratory to the nearly supernatural powers its believers claim it possesses to its dramatic unleashing upon our unsuspecting shores via the right arm of Matsuzaka.

Unfortunately, as with Godzilla, Mothra and their ilk, the gyroball might really be a juicy bit of fiction. But even if it is, the sheer mystery surrounding it and the what-if mind game between pitcher and batter likely will make hitters uneasy when they stand in against Matsuzaka.

The nonbelievers are vocal, though.

"There is no gyroball. I don't know who came up with that," says Mike Pagliarulo, a former big league third baseman who owns a scouting company that provides reports on Japanese players for major league teams. According to Pagliarulo, Matuszaka "doesn't throw anything that's any different from what anyone else throws.

"Oh, and he also doesn't wear a cape and doesn't fly."

Bobby Valentine, manager of the Chiba Lotte Marines, is more direct: "No such pitch," he says.

Pagliarulo and Valentine are wrong about one thing, however. There is, in fact, such a thing as the gyroball. The real question is whether it exists in any sphere other than the theoretical.

Around 2000, Japanese physicist Ryutaro Himeno, with the assistance of a baseball trainer named Kazushi Tezuka, used a computer to "invent" a new pitch that, instead of traveling with the backspin of a fastball or the topspin of a curve, would move with side spin, like a football or a bullet, so that the "spin axis" and the direction of travel would be the same. That spin would be achieved, Himeno and Tezuka explained in a book, through the laws of "double-spin mechanics."

According to the lore surrounding the pitch, which Himeno and Tezuka named the gyroball, it would behave unlike any other pitch in baseball. Depending upon which version of the story you accept, it would have either an exaggerated drop or an exaggerated side-to-side motion. Or perhaps both, depending upon the arm angle.

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Will Carroll, an expert on pitching injuries and a writer for BaseballProspectus.com, is the gyroball's leading champion in the United States, and he insists it is real. His view received support last week when Tezuka demonstrated the pitch during a visit to Arizona.

"I can teach it in 10 minutes," Carroll says, and in fact he has taught it to a handful of amateur and low-level professional pitchers. "Perfecting it? That takes a lot longer. As the pitch becomes more of a known quantity and as more people learn how to throw it and, more important, teach it, we'll see who the Bruce Sutter of the gyroball is."

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Steve Palazzolo, a Brewers minor leaguer who learned the gyroball from Carroll, also says it is real but acknowledges he has never thrown one in a game.

"It's a real pitch, and it's effective when it's thrown properly," he says. "But I don't know if it's going to be groundbreaking or revolutionary. It would take someone learning to master it."

OK, the gyroball exists as a textbook theoretical and perhaps as a goof-around pitch that any curious pitcher can learn. But is it really something new, or is it merely a geeky, scientific twist on an already established pitch? If the latter is the case, there clearly is no consensus as to which pitch it actually is.

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"I believe it is a screwball," says Buck Martinez, who managed the U.S. team in last spring's World Baseball Classic, for which Japan's Matsuzaka was named most valuable player.

"It's a changeup," says Robert Kemp Adair, professor emeritus of physics at Yale and author of The Physics of Baseball. "Put another way, it's basically nonsense."

"This pitch," says Alan Nathan, a physics professor at the University of Illinois and a specialist in the study of baseball physics, "is something like a cut fastball but with more drop to it."

Well, that clears it up.

But it gets even more confusing because the gyroball Matsuzaka is supposedly throwing in grainy videos that have been a staple of Internet chatter for years is, in fact, his excellent slider -- one of six "traditional" pitches he is known to throw.

Of course, this mystery could be cleared up if Matsuzaka were more forthcoming about his use (or nonuse) of the gyroball. But he obviously enjoys the cat-and-mouse game -- and whatever psychological edge it offers -- too much to come clean.