The World Series opens in Detroit tonight, and that means it's time for pitcher paranoia.

The particular fear and loathing at issue will occur whenever the pitcher has a chat with his catcher or other players on the mound. With well-choreographed movements, they will inevitably cover their mouths with their gloves while they talk.

	Kyle Ericson, Associated Press
	Milwaukee Brrewers pitcher Ben Sheets. Left, and catcher Mike Rivera hide their mouths while speaking on the mound during a game against the Cardinals in St. Louis last month. Related articles Cook: A special manager has his team at a special place World Series Preview: Young arms to open the World Series

The practice, which has become almost automatic in recent years, is designed to keep someone on the other team from reading their lips and stealing valuable information.

But there are at least three problems with this ritual.

First, there are no documented instances where someone was able to read the pitcher's and catcher's lips and relay critical information to a batter before the next pitch.

Second, even the best lip readers -- most of whom are deaf -- can only pick up about 60 percent of spoken words. The average person can detect about 10 percent of the words.

And finally, a lot of what is discussed on the mound might not be worth hearing, anyway.

Pirates pitching coach Jim Colborn said that "a lot of times when I go out to the mound, I'm just trying to get the guy to relax, or I'm trying to help the pitcher and catcher get refocused."

But there are times when he talks about pitch selection.

"You might say 'Go after this guy, or throw this first pitch in there, and if the hitter knew he was going to groove it," that could give him an advantage.

Mr. Colborn pitched in the Major Leagues for 10 years in the 1970s, and he remains skeptical about the value of mitt muttering because players in his era managed to do just fine without it.

Still, he put a little more stock in the technique when he joined the Los Angeles Dodgers as pitching coach in 2001, after learning that Dodgers broadcaster Vin Scully had a knack for reading lips.

There are indeed people who are much better than average at reading lips, and scientists don't quite understand why, said Ken W. Grant, a research audiologist at Walter Reed Army Medical Center in Washington, D.C.

One big problem with lip reading, Dr. Grant said, is that certain sounds -- b, p and m for instance -- look exactly the same when the lips form them, so even a good lip reader would have trouble distinguishing among "bat," "pat" and "mat."

But context is important, too, he said, so that if someone said, "The cat chased the m----," a lip reader wouldn't have much trouble guessing the last word is "mouse."

For that reason, he said, a skilled lip reader might have a better than average chance of understanding conversations on the baseball mound because the vocabulary might be more limited.

But there's not much objective evidence to back that up, said Paul Dickson, author of the 2003 book, "The Hidden Language of Baseball: How Signs and Sign Stealing Have Influenced the Course of Our National Pastime."

Mr. Dickson said he knows of no cases where someone has been able to read lips and relay valuable information to the other team.

Talking into gloves was obviously spurred by the increase in the number of TV close-ups during games, he said, and it has now spilled over into football, where many coaches on the sidelines routinely hold their clipboards in front of their mouths when they talk.

But in baseball, at least, Mr. Dickson thinks the ritual has about as much impact on the game as spitting. "I think there are many things that happen in baseball because they look cool, but it's just ballet."

It's unclear who invented mitt chat, but Jim Brosnan, a pioneering baseball author who pitched in the Major Leagues from the mid-1950s to the mid-'60s, said he couldn't remember a single player from his years who did it.

"I never did it. I think it's silly," said Mr. Brosnan, author of "The Long Season" and "Pennant Race."

The mound conversations he remembers best wouldn't have been of much use to the opposing squad anyway.

"A lot of times when a coach came out," Mr. Brosnan recalled, "he'd say 'Why did you do that? What possessed you to throw that pitch?' "

On one occasion when he was pitching for the Cincinnati Reds, Mr. Brosnan said, manager Fred Hutchinson came to the mound just to tell him "that's the worst [expletive] job of pitching I've ever seen," and then took the ball from him.

Mr. Brosnan was so angry as he walked to the dugout that he hurled his glove into the home stands, "and then, they wouldn't throw it back -- they were afraid I'd get another chance."

His ignominious departure came after he had thrown a hanging curve ball that a hitter knocked out of the park. It was a pitch, he noted drily, "that he could have hit without any previous information."

The glove cover-ups may not have much evidence behind them, but they're part of a long tradition in baseball of using signs and then trying to steal them.

The subject has gained new visibility recently with the publication of "The Echoing Green" by Joshua Prager, a book built around the famous 1951 home run hit by the New York Giants' Bobby Thompson against the Brooklyn Dodgers' Ralph Branca to win the National League pennant.

Mr. Prager's book details how the Giants were routinely putting a player with a telescope in the center field clubhouse to steal the catcher's signs, which were then sent electronically to the bullpen, where a pitcher would either toss a ball in the air or not, depending on what pitch had been called.

That kind of information could give a big-league hitter a distinct advantage, said the Pirates' Mr. Colborn.

Whether anyone could get that kind of an edge by reading lips, though, is an open question, he said.

So he concedes this much:

"When I go to the mound and I'm saying something, I try to keep my lips from moving. In other words, I do ventriloquism coaching."

And then he added, tongue planted firmly in cheek:

"And when I have to chew the pitcher out, what I do is, I do it in Freddy Sanchez' voice, and then they won't get mad at me -- and they won't get mad at Freddy, either, because everyone likes Freddy."