The boost a slugger gets from a corked bat is highly overrated. In fact, experts on the physics of baseball say such bats reduce a hitter's power.

"You have a slightly lighter bat and you're going to hit the ball a little less far,'' said retired Yale professor Robert K. Adair, the author of "Physics of Baseball.''

The science and practice of corking bats is under new scrutiny following the ejection of Sammy Sosa from Tuesday night's game between the Chicago Cubs and Tampa Bay Devil Rays.

Adair contends a corked bat actually may reduce by about 3 feet what would have been a 375-foot drive from a conventional wooden bat. While corked bats can increase bat speed and improve timing, he believes the benefits are minimal.

"This is not something that radically changes the game,'' Adair said Wednesday. "There's probably more superstition involved.

"You may hit the fastball a little more often. It's so marginal.''

A study at the Baseball Research Center at the University of Massachusetts-Lowell found the speed of corked bats increased just more than 1 mph, or about 1 percent.

Sosa, who has 505 career homers, was the sixth major leaguer to be disciplined for a corked bat since 1997. He said he accidentally used a bat intended for batting practice. His bat broke in half when he hit a ground ball in the first inning of the Cub's 3-2.

Alan Nathan, a physics professor at the University of Illinois, also played down the benefits a long-ball hitter can derive from a corked bat.

"If your goal in life is to hit home runs, then I don't think a corked bat is going to help you too much,'' said Nathan, who has published studies on the subject. "On the other hand, if you're sort of a contact hitter, a singles hitter, then a corked bat probably can help you.''

A quicker swing means a batter can watch the ball longer before taking a cut.

"The longer you watch it, the more information you have as to how you want to swing at it,'' Nathan said.

Adair said the standard way for players to cork a bat is to drill a hole about 6 inches down the length of the bat and add cork, high-bouncing rubber balls or "whatever their fancy is.'' Sosa's bat contained a half-dollar size piece of cork about halfway down the barrel.

Baseball players are famously superstitious, and if a player succeeds with a corked bat once, he is apt to use it again. Also, the reputation of corked bats have a strong hold on players looking for an advantage.

"Let's say you're expected to hit about .250 and about June 4 you're batting .205,'' Adair said. "Your timing is off, you can't seem to hit and you see your $2 million going out the window. You take an ounce off the bat and maybe it makes a difference.''