The Whys and Hows of Bat and Ball Regulation
By: J.J. Trey Crisco, Ph.D. and Rick Greenwald, Ph.D. National Institute for Sports Science and Safety
USA Baseball Medical/Safety Advisory Committee
June 2000

Why regulate baseball bat and ball performance?

By far the most compelling reason for regulating bat and ball performance is the possibility of serious injury to pitchers and fielders from being hit with the batted ball; higher performance implies higher batted ball speed, less time to react to the batted ball, and a greater likelihood of contact. Injury data from the NCAA Injury Surveillance System (ISS) and the National Center for Catastrophic Sports Injury Research have found no rapid or gross increase in severe injuries.

These databases, however, do not have the ability to detect slow or subtle increases in injuries, and further surveillance needs to be conducted. Another reason for regulating baseball bat and ball performance is the preservation of the balance between offense and defense. Such regulation is clearly the role of a sports governing body. While the level of regulation is subjective, it is essential that the test method for regulation follow established scientific practices, as discussed below.

How NOT to regulate bat and ball performance.

As of January 1, 2000, the NCAA mandated regulation of baseball bats using performance measurements from the Baum Hitting Machine (BHM) at the University of Massachusetts Lowell. However, no public disclosure of the methodology, calibration, or validation of the BHM has been made. In 1999, an NCAA Baseball Research Panel, composed of academicians and scientists, supported the use of the BHM as a test standard (NCAA Press Release 9/28/1999) - despite objections regarding the lack of any publicly available scientific data. As the panel has failed to publicly disclose any of their findings or the basis for their recommendation, one can only conclude that scientific issues were not the foundation of their recommendation.

Flaws in the use of the BHM to effectively determine bat performance became public when Dr. Jim Sherwood, director of the Lowell facility, and the NCAA Baseball Research Panel, expressed his belief that the manufacturers had discovered a loop hole in the NCAA test (NCAA News, 4/10/2000). By decreasing a bat's swing weight, a failed bat could then pass the test., It has been shown, however, that decreased swing weight increases bat performance, resulting in higher batted ball speeds. This information had been openly discussed and presented to the NCAA in 1997 (Fleisig et al., 1997; Koenig et al., 1997).

In short, the BHM's reliability has not been shown, the test has not been validated in any way, and is not an independent, available test apparatus. It should not be considered as an apparatus for standardization of bat or ball performance.

How SHOULD baseball bat and ball performance be regulated.

Regulation must be done using test methods that are both publicly available and validated. This is the basis for all scientific practices. The method should be validated against what is truly occurring in the field. This approach has been supported by the manufacturers of baseball bats, who funded our research program to accurately measure batted ball speed in a batting cage study (study results can be found at The Lansmont Corporation (Lansmont Bat and Ball Verification Center, Sunnyvale, CA) has developed a test machine that is capable of measuring bat performance at higher impact speeds. All specifications of the Lansmont device are publicly available (Gilman, 1999).

Furthermore, we have collaborated with Lansmont to validate their apparatus by comparing the results of the NISSS field study measurements (Crisco and Greenwald, 1999) with Lansmont laboratory tests done using identical bats and balls. How to make a metal bat perform like a wood bat. The long held belief that metal bats can out perform wood bats has only recently been validated scientifically (Crisco and Greenwald, 1999; Crisco et al., 2000; Greenwald et al., 2000). In this batting cage study, some metal bat models clearly out performed wood bats in both batted ball speeds and in the number of higher speed hits, while other metal bats performed similarly to wood. We believe that to make a metal bat, or any non-solid wood bat, perform like a wood bat, the bat must have similar total weight, swing weight (measured as the balance point or moment of inertia), and barrel performance. Other factors, such as bat shaft flex, are likely to influence bat performance, but these factors are even less well understood.

Is it the ball?

Despite the obvious fact that ball contact causes injury, governing bodies have turned to regulation of the bat. Players get hit when the game is played with wood bats as well as with metal bats. Decreases in baseball hardness and ball weight have a significantly greater effect in reducing injury severity than regulating metal bats to perform like wood bats (Crisco et al., 1997).

What to do?

Increases in batted balls speeds may lead to more frequent and severe injuries from contact with the batted ball. Injuries are part of sports, and the determination of an acceptable level of risk at a local, state, regional, and national level rests with the players, coaches, parents and governing bodies. If the risk is considered too great, regulation of bat and ball performance is a justifiable course of action. However, the labratory test methods used for regulation must follow well accepted scientific guidelines.

Acknowledgements: Our laboratory has received funding from the NCAA, the NFHS and the SGMA. The opinions expressed in this report are solely those of the authors, and may not represent the opinions of any of the funding entities.

References: Please see the web site www.nisss.or