PREDICTORS OF FIELDING PERFORMANCE IN PROFESSIONAL BASEBALL PLAYERS.
Gerald T. Mangine1, Jay R. Hoffman, FACSM1, Adam R. Jajtner1, Adam M. Gonzalez1, William P. McCormack1, Adam J. Wells1, Jeremy R. Townsend1, Nadia S. Emerson1, Edward H. Robinson, IV1, Jose Vazquez2, Napoleon Pichardo2, Maren S. Fragala1, Jeffrey R. Stout, FACSM1.
1Institute of Exercise Physiology and Wellness, University of Central Florida, Orlando, FL ; 2Texas Rangers Baseball Club, Arlington, TX.
SUMMARY & PRACTICAL APPLICATIONS
BACKGROUND: Fielding performance is difficult to assess, as traditional measures of fielding percentage (FPCT) and range factor (RF) do not take into account in-game activity. The ultimate zone rating extrapolation (UZR/150) rates fielding performance by runs saved or cost within a zone of responsibility, in comparison to the league average (150 games) for a position. Spring training anthropometric and performance measures have been previously related to hitting performance, however their relationships with UZR/150, FPCT, and RF are unknown.
PURPOSE:Examine the relationship between anthropometric and performance measurements on fielding performance in professional baseball players.
METHODS: Body composition [3-site skinfold (chest, abdomen, and thigh)] and performance measurements (grip strength, 10-yard sprint, pro-agility, and vertical jump) were collected during spring training over the course of five seasons (2007-11) for professional corner infielders (CI; n=17, fielding opportunities=420.7±307.1), middle infielders (MI; n=14, fielding opportunities=497.3±259.1), and outfielders (OF; n=16, fielding opportunities=227.9±70.9). The relationships between these data and regular season (100-opportunity minimum) fielding statistics were examined using Pearson correlation coefficients and stepwise regression analyses.
RESULTS: Significant correlations were observed between UZR/150 and body mass (r=0.364, p=0.012), LBM (r=0.396, p=0.006), VJPP (r=0.397, p=0.006)), and VJMP (r=0.405, p=0.005). Of these variables, stepwise regression indicated VJMP (R=0.405, SEE=14.441, p=0.005) as the single best predictor for all players, though the addition of pro-agility performance strengthened (R=0.496, SEE=13.865, p=0.002) predictive ability by 8.3%. The best predictor for UZR/150 was body mass for CI (R=0.519, SEE=15.364, p=0.033) and MI (R=0.672, SEE=12.331, p=0.009), while pro-agility time was the best predictor for OF (R=0.514, SEE=8.850, p=0.042). Relationships with FPCT and RF varied among all players and position.
CONCLUSIONS: Spring training measurements of VJMP and pro-agility time may predict the defensive run value of a player over the course of a professional baseball season.
Table 2.Selected bivariate correlations between fitness components and measures of fielding performance by defensive category.
Table 1.Anthropometric and Performance Comparisons
THE SINGLE BEST PREDICTORS
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Regression Analysis of the Ultimate Zone Rating/150
All Players: VJMP (R=0.405, SEE=14.441, p=0.005)
Infielders: Body Mass (CI: R=0.519, SEE=15.364, p=0.033; MI: R=0.672, SEE=12.331, p=0.009).
Outfielders: Pro-agility time (R=0.514, SEE=8.850, p=0.042)
Regression Analysis of Fielding Percentage
All players: Height (R=0.296, SEE=0.012, p=0.043)
Corner Infielders: Age (R=0.512, SEE=0.016, p=0.035)
Outfielders: Maximal grip strength (R=0.527, SEE=0.242, p=0.036)
Middle Infielders: None
Regression Analysis of Range Factor
All players: BF% (R=0.313, SEE=2.441, p=0.032)
Corner Infielders: Age (R=0.544, SEE=2.556, p=0.024)
Outfielders: 10-yard sprint time (R=0.527, SEE=0.242, p=0.036)
Middle Infielders: None
Figure 1. The field of play is broken up into 78 zones of responsibility used for calculation of UZR/150. The fourteen furthest from home plate not included in the calculation.
The purpose of this investigation was to identify the anthropometric and physiological variables that may predict fielding performance across defensive positions in professional baseball.