Using baseball card prices to measure star quality and monopsony

Abstract

Baseball card prices are used to capture star quality in a new measure of productivity in Major League Baseball. Star quality, which impacts revenues, is determined from a player's baseball card price as the residual in a fit of card prices to performance statistics. This measure is entered into the computation of individual player marginal revenue product and compared to players' salaries using data from the four years leading up to the 1994 MLB strike. Results are examined for monopsonistic exploitation by market size, free agency status, type of player, and other relevant categories. Underpaid and overpaid players are identified.