Crack, Ping; Same Thing?
April 11, 2007

Copyright 2007 Times Herald Record (Middletown, NY)

An unmistakable sound of spring — the ping of a baseball hitting an aluminum bat — may not be heard at New York City high school games.

The City Council voted to ban the bats for safety reasons, Mayor Michael Bloomberg threatened to veto the law, and the Council responded with a promise to override. Thus, the long-running "aluminum vs. wood" debate is back in the national spotlight.

The thing is, if bats meet the standards set by the governing bodies for college, high school and Little League baseball, the playing field is level. Approved wood bats and approved metal bats put balls into play at just about the same speed.

The real issue is that aluminum bats have a big sweet spot that turns mediocre contact into a pretty decent shot. So there is an advantage with aluminum, but it's that more hard hits get into play, not that the ball goes faster.

There's plenty of evidence to support that point. There are countless stories of dramatically reduced statistics in baseball leagues that have instituted a wood-only rule.

Here's a look at the ways the metal vs. wood issue is dealt with:

Two terms you need to know

Ball exit speed ratio (BESR): A formula that combines the speed — in a controlled setting — of the ball leaving the bat, of the pitch and of the swing. Colleges and high schools rely on a BESR number to determine if a bat is OK to use at those levels of play.

Bat performance factor (BPF): A formula that combines the pitch speed and rebound speed — in a controlled setting — from a rigid surface, and from a stabilized bat that "gives" on contact to determine ball exit speed. Little League uses BPF numbers to decide which bats are approved.

College baseball's stance

Bat testing began in 1999, with the idea of creating limits for non-wood bats that simulated the top performance of the best wood bat.

A 34-inch, 31-ounce solid ash bat, with contact measured six inches from the tip in a controlled setting, resulted in a ball exit speed of 96 mph. Dr. James Sherwood, professor of mechanical engineering and director of the Baseball Research Center at the University of Massachusetts-Lowell, conducted the test.

Sherwood then tested aluminum bats with the same "minus-3" length-to-weight ratio, using the BESR, to create a standard that limited ball exit speed up to 1 mph faster than wood.

Every model of non-wood bat used in college and high school baseball today has gone through Sherwood's lab.

"Taking the same weight-proportioned wood and non-wood bats, the non-wood will have ball-exit speed up to 1 mph faster," Sherwood said. "However, if the non-wood bat's weight is distributed throughout the bat more — the center of gravity closer to the hands — it will feel lighter, and the swing can be 2-3 mph faster."

The NCAA also has rules that regulate weight distribution, Sherwood said.

Nearly all college baseball players use aluminum bats, but a wood-bat-only league does exist — the Northeast 10.

High schools' stance

The National Federation of High Schools employs the same bat standards used in college baseball.

New York City schools compete in the Public Schools Athletic League. Local high schools are members of the New York State Public High School Athletic Association. PSAL schools don't compete in the state public high school tournament.

There are no impending changes coming from NYSPHSAA regarding bat rules, assistant director Lloyd Mott said.

"The city situation seems to be political," Mott said. "If somebody has some good scientific evidence, we would love to see it."

Mott said the state charted pitcher injuries from line drives during the 2004 and '05 seasons.

"There were very, very few injuries. Practically no severe injuries," Mott said. "There wasn't enough evidence to change, so we're leaving the rules as they are."

Mott also pointed to Massachusetts banning metal bats from its championships recently, then revoking the ban after one year.

Little League's stance

In light of the New York City situation, Little League of America reiterated its position on its Web site, saying it "advocates" the use of wood or non-wood bats.

"Little League International," the Web site reads, "does not accept the premise that the game will be safer if played exclusively with wood, simply because there are no facts — none at all — to support that premise.

"As a result, any individual or league choosing the wood-only option must understand the choice is not being made because of any factual or scientific information."

No local Little Leagues are wood only, according to District 19 administrator John Ward.

There are no national Little League restrictions on weight-length differential, nor does it use the BESR for determining if a bat is legal. Instead, it uses the BPF. The standard wood bat's rating is 1.00. A very good wood bat's BPF is 1.15. A non-wood bat can't have a BPF higher than 1.15, and by 2009, all bats used in Little League must be imprinted with the BPF.

Professor Alan Nathan of the University of Illinois at Urbina-Champaign, an expert in the field, isn't a fan of the BPF.

"It doesn't measure the moment of inertia," Nathan said, explaining that the formula doesn't use swing speed like the BESR. "That's a very important element. Does that make a difference as far as safety is concerned? I really can't say."