Get on the Nerdy Side of Baseball with New Testing Method


If you’re like me, your mind raced through a number of possibilities when you first learned of the formal adoption of ASTM F2845. What? This is the first you’re hearing about it?

ASTM F2845, Test Method for Measuring the Dynamic Stiffness (DS) and Cylindrical Coefficient of Restitution (CCOR) of Baseballs and Softballs was announced on August 16, 2010 to replace older testing methods that proved to be less accurate compared to real world applications.

Dynamic stiffness is another name for the baseball’s hardness. The other subject of this ASTM standard is the Cylindrical Coefficient of Restitution; I will defer to the ASTM International press release for this explanation:

"The cylindrical coefficient of restitution, or bounciness, measures the rebound of the ball following its impact with a bat or another cylindrical object. Bouncier balls tend to be more elastic, which means that when a ball is deformed by a collision, it will reform and rebound, returning the kinetic energy of the impact into motion in the opposite direction."

Think of the difference between shooting a rubber band off your finger and trying the same thing with a ring of string. The rubber band will obviously fly much farther due to its elasticity.

The physical properties identified in this standard struck me as the defining factors in the so-called “live-ball” and “dead-ball” eras. Small variations could have a tremendous impact on the flight of the ball after contact with a bat. My mind raced through possible implications for the game at the major league level. Could a new testing method narrow the band of variation between baseballs?

As it turns out, ASTM F2845 does not appear to have big implications for the MLB game. After contacting the committee staff manager, I received the following response from Lloyd Smith, an associate professor in the School of Mechanical and Materials Engineering at Washington State University:

"ASTM F2845 was primarily developed for amateur softball and baseball. Ball stiffness has a large effect on the performance of hollow bats used in these sports. In MLB, bat performance is nearly independent of baseball stiffness. It is possible the MLB will use F2845 to monitor balls, but it is unlikely that it would have an impact on the game. In MLB the ball weight and coefficient of restitution are more important than stiffness, and current standards to measure these properties work quite well."

I am left with a somewhat unsatisfied feeling. We may never know the full extent to which performance-enhancing drug use had on the game and it feels as though similar uncertainty exists in regards to the game’s equipment. We can be fairly sure that variations in the manufacturing of baseballs has occurred over time. Was there a point in time that MLB was able to standardize the manufacturing process from year-to-year and era-to-era? Has MLB actually tinkered with the ball to produce intended results? We may never know.

The full standard is available at the ASTM International website.