Slugger or slacker: A sabermetric assessment of free agency on Major League Baseball player performance

This study analyzed Major League Baseball player performance using sabermetric measurements of offensive productivity in order to determine how player production was impacted as a result of free agency. The theoretical framework for this research is based on two competing theories of social and organizational behavior: J. S. Adams' Equity Theory and Victor Vroom's Expectancy Theory. Both equity theory and expectancy theory were developed to predict worker performance under conditions of inequity in terms of under-reward and over-reward.; Sabermetric measurements, OPS, Runs Created, and Win Shares, were utilized to assess performance improvements or decrements for players in each of the following three years: (1) pre-option year---the year prior to a player becoming a free agent, (2) option year---the last year of a player's contract, and (3) post-option year---the first year of a player's new contract. Subjects consisted of Major League Baseball free-agents who signed multi-year contracts of at least two years or more with a their current team or another major league franchise between the years of 1976 and 2003 (n = 234). In order to qualify for inclusion, players must have had a minimum of 250 at-bats in each of the three individual years being examined: pre-option year, option year, and post-option year. Covariates, age and team winning percentage, were incorporated into this study in an attempt to control for specific factors thought to impact individual player performance.; Results of multivariate analyses of variance (MANOVA) with repeated measures revealed that free agency had a significant impact on each of the three performance measures. Follow-up univariate analyses of variance (ANOVA) indicated that player performance significantly declined for each of the dependent variables following free agency. When controlling for age, multivariate analyses of covariance (MANCOVA) revealed no significant effects with regards to the impact of free agency on player performance. When controlling for team winning percentage, however, multivariate and univariate analyses indicated that post-option year team winning percentage significantly affected the impact of free agency on player productivity. For each of the dependent variables, significant findings were consistent with expectancy theory predictions.