Do MLB hitters engage in opportunistic behavior?

The possibility of opportunistic behavior by workers in the labor market follows from utility maximization theory and expectation theory. Opportunistic behavior means that workers seek to take advantage of labor market conditions to better their economic standing, perhaps to the detriment of the organization.  For example, given tenure as a labor market phenomenon in higher education, opportunistic behavior suggests untenured professors may work arduously to obtain tenure and then slack off after tenure is granted. Measuring such behavior is difficult because productivity measures, salaries and contract information are not often publicly available.  Professional sports markets, however, can provide fertile testing grounds since pay, player productivity statistics and contract details are publicly obtainable.  To wit, major league baseball (MLB) players may engage in opportunistic behavior by shirking or slacking off in their effort after signing a long term guaranteed contract, since their pay is not tied to their performance.   The opposite is the case in the contract year, the year before a player can negotiate a new contract with any team. Players may increase their effort during the contract year to gain greater interest from teams in hopes of procuring a better future contract.  Using ordinary least (OLS) and pooled (OLS) estimation, previous studies of opportunistic behavior in professional baseball and basketball produce conflicting conclusions. By using appropriate econometric analysis specifically designed for panel data, my paper will correctly show whether opportunistic behavior occurs.