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Optimum Performance: Does size matter to offensive performance in MLB?

Portrait Hall of Fame shortstop Ozzie Smith chats with Mackie Shilstone at “The Fitness Principle” center at East Jefferson Hospital. KATHY ANDERSON / THE TIMES-PICAYUNE (KATHY ANDERSON / THE TIMES-PICAY)

Does size really matter when it comes to better offensive performance at the Major League (MLB) level? Having worked for the San Francisco Giants as their Performance Conditioning and Nutrition consultant from 1989 to 1999 – along with hundreds of other MLB players like Hall of Fame St. Louis Cardinals shortstop Ozzie Smith, it does in certain instances.

Smith came to me specifically to increase his “weight” to enhance his hitting ability, so he could be known as a “well-rounded player,” despite having won more golden gloves at his position than I can count. As the long professional baseball season would progress, some players, especially in August, experienced bat fatigue. In Smith’s case, his body weight would drop during the season from 155 pounds down to 144 – dropping his bat speed.

When Smith came to me at the age of 31, his batting average was 249. The first year after we put into motion a performance enhancement plan, which increased his scale weight to 175 (mostly lean muscle), he hit 303. During the next eleven years, Smith’s batting average climbed to 289.

Story by

Mackie Shilstone,

Contributing writer

“Changes in Physical Size Among Major League Baseball Players and Its Attribution to Elite Offensive Performance” – a research study which appeared in the October 2014 issue of the Journal of Strength and Conditioning Research – sought to examine longitudinal trends, as to how the size (height, weight, BMI) of MLB players might effect offensive performance.

Researchers from the Baltimore Orioles, the Department of Kinesiology and Health Education from the University of Texas at Austin, and the Department of Kinesiology from the University of Waterloo in Canada, “identified the height, weight, BMI (body mass index) changes in the normal MLB population, as well as, offensive league leaders (OLL) over 3 separate seasons within the modern baseball era (1970,1990, and 2010).”

The OLL group consisted of all players who met at least 1of the following statistical criteria: total homeruns, slugging percentage, batting average, on-base percentage, runs scored, runs batted in, and on-base plus slugging percentage. The reference (comparison) MLB group did not include any OLL players.

While no human subjects were involved in the study, “all performance statistics, age, body weights, and heights were obtained from”

The researchers found that, “overall, nearly 10 kg (22 lbs.) of body mass was gained form 1990 to 2010, representing approximately a 12% increase. Whereas height displayed smaller growth patterns showing no more than 3 cm (centimeter) growth, representing less than 2 % increase.”

There was a slight drop in the height of the OLL players from 1970 to 1990, which  researchers said that in successive years was “perhaps associated to the influx of Latin players from 1990 onward.” These players were shown to be shorter than players of non-Latin descent.

Prior research demonstrated that, “U.S. players born between 1979-1983 achieved a mean body weight of 195.7 lbs,” while the 2010 findings, “showed players approximately 10 pounds heavier, weighing over 206 lbs, which documents the largest professional baseball population to date.”

The, “OLL were found to be taller, heavier, with greater mass proportionality over successive years when compared with the MLB reference cohort.” Note that this study did not factor in body composition (lean/fat ratio) to the statistics.

You also have to include the fact than in the 1990’s more strength and conditioning coaches or consultants, such as myself, were added the support staff of MLB teams.

As a result, MLB players were provided with in-season and off-season performance enhancement programs, along with dietary counseling that had a significant impact on player performance.

Despite the growth in size of MLB players, you cannot let technological advancement – playing surfaces, bat design, or muscle growth – out run the human body, because that’s when players of any size can get hurt.

Mackie Shilstone, a regular contributor to | The Times-Picayune, has been involved in the wellness sports performance industry for nearly 40 years. He is currently a fitness consultant to Serena Williams and has trained numerous other professional athletes and consulted a litany of professional sports franchises. He is St. Charles Parish Hospital’s fitness and wellness expert. Contact him at