Guest post: Researchers, players disagree on optimal baseball bat weights

Photographs of Babe Ruth often capture the slugger gripping a bat, if not two, that resembles a troll’s club in length and thickness. With such a mass of lumber, one is tempted to think, it’s no wonder the guy hit 714 home runs.

But according to physicists, heavy bats can be detrimental to a player’s swing. One study, based on the calculation of bat speed, estimates that the average professional baseball player should swing a 31.1-ounce bat and the average college baseball player a 29.4-ouncer, but players at both levels often drastically exceed those guidelines.

Heavy bats, in fact, are ingrained in baseball lore.

Early-20th century star Frank “Home Run” Baker used a 52-ounce bat, according to Baseball: The Biographical Encyclopedia, and the Louisville Slugger company once sold bats weighing more than 45 ounces to many players, including eventual Hall of Famers Baker and Edd Roush.

But the end of the Deadball Era in the 1920s led to an emphasis on power over contact and an influx of lighter bats, according to P.J. Shelley of the Louisville Slugger Museum & Factory.

Then came Hall of Famer Ted Williams, a student of the game and one of history’s greatest hitters. Shelley says Williams, who mostly ordered bats between 32 and 34 ounces during a career that lasted from 1939 to 1960, was “one of the first to recognize that bat speed is more important than the weight of the bat.”

From Williams until about 25 years ago, bat weights dropped further, and today’s average Major Leaguer swings about 31.5 or 32 ounces, according to Shelley.

Though most players now use lighter bats than their predecessors, some still believe the more mass the better. According to Shelley, the Los Angeles Angels’ Josh Hamilton and Los Angeles Dodgers’ Hanley Ramirez swing 34.5- or 35-ounce bats, among the heaviest in the Major Leagues. And one Chicago Cubs player recently made headlines for his weighty bat choice.

In June 2012, Chicago Cubs left-fielder Alfonso Soriano was persuaded by manager Dale Sveum to pick up a 32-ounce bat, after years of using a 33.5-ounce behemoth, according to the Chicago Sun-Times.

“He’s typically used one of the heaviest bats in baseball most of his career,” Sun-Times reporter Gordon Wittenmyer said. “And you could make a case that’s part of his high-strikeout total, and it’s definitely part of his home run totals.”

Research supports Sveum’s suggestion that Soriano swing a lighter stick: In 1995, Terry Bahill and Miguel Morna Freitas of the University of Arizona developed a model that used bat speed to calculate ideal bat weight for any given baseball player. They also developed a simpler version using height, weight and age to estimate the optimal weight. According to the latter model, Soriano, at his listed height of 6 feet 1 inch, should use a 31.3-ounce bat, which, according to Bahill, would increase his contact rate.

“The 31- and the 33-ounce bat wouldn’t make a lot of difference in the distance the ball would go,” Bahill said. “But we think he could swing it more accurately if it were smaller.”

According to the Arizona duo’s study, the average college baseball player is best off with a 29.4-ounce bat, but Northwestern University baseball coach Paul Stevens said options are limited and most players use either 30- or 31-ounce bats.

NU shortstop Trevor Stevens is listed at 5 feet 9 inches, suggesting he should, according to Bahill’s model, swing a 29-ounce bat. But the switch-hitter uses a 31-ounce bat when he bats left-handed and a 30-ounce bat when he bats right-handed. He said those weights reflect what manufacturers produce and therefore what college players can access.

“There are bats that are weighted differently within the barrel and the handle,” Stevens said. “They feel lighter in your hands, but the ball doesn’t jump off of them as much.”

Stevens was referring to “moment of inertia” (or “swing weight” in baseball parlance), a parameter that measures the distribution of mass along the bat. Dr. Daniel A. Russell of Pennsylvania State University said a number of studies have proven moment of inertia more important than bat weight in bat choice.

“It’s not just how heavy the bat is, it’s how that weight is distributed,” Russell said. “You can take two bats that both weight 30 ounces and you’ll get very different behaviors depending on how the weight is distributed.”

Despite the available research, Wittenmyer said he has never heard anyone around the Major Leagues reference any studies on bat choice, suggesting the choices players make when choosing their equipment is more instinct than science.

Unscientific thinking may be advisable given the imprecision of the researchers’ conclusions. Bahill said his simplified model can only predict ideal bat weight within about two ounces and in order to get precise results, a player must come into his lab for measurements.

Hence what Shelley calls the true determinant of bat choice among baseball players of all ages.

“It’s a matter of player preference,” he said. “And what feels comfortable to them.”

The Bat Chooser: In 1995, Terry Bahill and Morna Freitas developed a method for choosing the right baseball bat, appropriately dubbed “The Bat Chooser.” This model calculated maximum bat speed using the force generated by a players swing and measured subjects across all levels of play. Because the original Bat Chooser required players to visit a laboratory for precise measurement, the researchers simplified their model to estimate ideal bat weight using height, weight and age. Later research brought into question the validity of these calculations.

 

Age (years); height (inches); weight (pounds)