When Gregor Blanco of the San Francisco Giants hit a line drive over center field smacking Tigers' pitcher Doug Fister right in the head last night in Game Two of the World Series, he almost certainly hit the "sweet spot," the part of the bat where the best hits usually come from.
The sweet spot is where the greatest amount of energy is transferred from the bat to the ball and, incidentally, where the hands feel the least vibration. This spot, also called the center of percussion, is generally found between 5 and 7 inches from the business end of the bat. Miss it, and you'll feel it. They don't call it "the sting" for nothing.
Bat companies have been scratching their heads for decades, trying to take the sting out of the swing. Daniel Russell, a professor of acoustics at Penn State University, thinks he's got it figured out. He's discovered that bat vibrations between 600 and 700 hertz are what cause the most pain, and "vibration absorbers" designed to dampen those oscillations can eliminate it. He presented his findings this week at the 164th meeting of the Acoustical Society of America.
Our hands are sensitive to frequencies ranging from 200 to 700 Hz, but previous damping techniques — wearing batting gloves, wrapping metal bats with leather and even vibration absorbers like those Easton has used in youth bats for a generation — came with drawbacks like added weight. Others, including Louisville Slugger and Worth, experimented with vibration dampers and two-piece bats for youth leagues.
The trouble is, earlier efforts focused largely on vibrations around 200 Hz, the oscillations felt by the lower hand on the bat. It did nothing to mitigate the sting felt by the upper hand, where the vibrations are closer to 700 Hz and cause the most discomfort.
Once Russell identified the problem, he worked with bat-maker Marucci Sports to develop a mass-spring vibration absorber for the company's youth and senior league bats. It's essentially a spring that counteracts the vibration of the bat.
"What is unique about the vibration absorber that I tuned for Marrucci Bats is that this absorber is specifically designed to target the second bending vibration instead of the first bending vibration as the earlier approaches were," Russell told Wired. "And this vibration absorber produces a damping effect that is about five to 10 times greater than any of the other techniques."
The damper is installed in the knob of the bat. Because the length of the bat effects the vibration, dampers are specifically tuned to suit each slab. Although Marucci has offered the dampers in youth bats for two years, Russell's data has only now been published. He's now looking at the implications for other sports with sticks, like field hockey, as well as the vibrational behavior of composite and aluminum bats.
The technology has been aimed primarily at kids to keep the little ones from being discouraged by the discomfort of a less-than-perfect hit. Marucci will now offer the absorber in its entire line of bats. But don't expect to see Sandoval or other big league players swinging a dampened bat. Major League Baseball allows only wood bats, and they can't be modified in any way.
"By the time a player reaches the minor or major leagues," said Russell, "he had better know how to hit the ball on the sweet spot, and can only blame himself if he gets stung by a poorly hit ball."
