Since metal bats were introduced to college baseball in 1974, guidelines have been introduced to make them less lively.

After the home-run-filled 1998 College World Series, in which USC beat Arizona State 21-14 in the championship game, steps were taken to adopt a BESR (ball exit speed ratio) standard to reduce the potency of metal bats.

Since 2003, the BESR standards have applied to metal bats at both the NCAA and high school level. Due to the standards, the bats are heavier — lessening bat speed — have smaller barrels and balls come off the bat with the same maximum exit speed (97 mph) as the top wooden bats.

Still, it is widely accepted that metal bats are livelier.

For starters, metal-bat critics roll their eyes at the testing conditions used to determine the maximum exit speed of 97 mph. The conditions — a 70 mph pitch and a 66 mph swing speed — are much slower than typical conditions even at the high school level.

In addition, metal bats have qualities that make them more potent than wood. In metal bats, weight is distributed more evenly, so they are easier to swing fast. Metal bats, which are hollow, also tend to compress like a spring when striking a ball. This causes the ball to jump off the bat in what researchers have termed the "trampoline effect."

Sonoma Valley High School coach Don Lyons often uses wood bats in practice. And he's seen his players toss them aside during batting practice in favor of metal ones.

"There is concrete evidence to me in working with high school athletes who will hit with wood and switch to aluminum on the next swing," Lyons said. "It's decidedly different. The ball just comes off the bat harder with aluminum."

University of Illinois physics professor Alan Nathan has done extensive research on the physics of the bat-ball collision and bat performance. He also serves on the NCAA Baseball Research Panel, an unpaid position in which he helps advise the NCAA on bat-performance issues.

Nathan doesn't take sides on the metal vs. wood bat issue. But he will say this: If he had a son who was a pitcher, he wouldn't fear for his safety in a metal-bat game.

"Do aluminum bats outperform wood bats as currently regulated by the NCAA? Yes. That's been well documented," Nathan said. "But that amount by which they outperform wood bats has been regulated and estimated very well, to within about 5 percent. That 5percent gap, there's no secret about it. I'll leave it to others to determine whether that 5percent gap is significant."

Of course, parents such as Bjorn Sandberg and Debbie Patch would say every millisecond matters.

And Nathan said that 5 percent gap will "essentially become zero" when new bat standards are introduced at the NCAA level in 2011 and the high school level in 2012.

Nathan developed the new BBCOR (ball-bat coefficient of restitution) standards, which he says are a more natural and direct way to regulate the bat. BBCOR bats, which are not currently available, will be designed to produce wood-like performance as closely as possible.

In other words, every metal bat currently used at the NCAA and high school level will be illegal in 21 months.

Joel Swanson, the baseball coach at Shanley High in Fargo, N.D., believes BBCOR bats could help diffuse the bat debate. Swanson has conducted a six-year wood-bat statistical study and helped write the proposal when North Dakota became a wood-bat state in 2007. He says it's possible the state would use BBCOR bats instead of wood in the future.

"If it works, it could be the solution to everything," Swanson said. "This could make the problem go away real fast."

Elliot Hopkins, assistant director of the National Federation of State High School Associations, said the NFHS isn't following the NCAA's lead on BBCOR bats in response to perceived safety issues. There have been five catastrophic baseball injuries reported to the NFHS in the past 17 years.

"We're always wanting to minimize risk as much as possible," Hopkins said. "But is this a case where I say &‘Wow, now that we have the BBCOR standard I can rest easier at night?' No. Because it's still a situation where there are batted balls and there's a question of reaction time. Will a pitcher get out the way and knock it down? That's the unknown variable."

You can reach Staff Writer Eric Branch at 521-5268 or eric.branch@pressdemocrat.com