Free agency has created a controversial revolution in professional athletics since the 1980s. Free agency is the ability of professional team athletes to change teams when their contracts expire. Players can entertain offers from the teams interested in signing them and choose from the available choices. In theory, players use the principles of a free-market economy to receive salaries commensurate with their abilities. Some pundits believe that free agency has been extremely beneficial to professional sports, allowing the best players to be paid what they are worth. Others argue that the dramatic increases in salaries and the tendency of players to change teams every few years has been detrimental.

For most of the history of professional athletics, players were forced to stay with the team that drafted them through a "reserve clause" in their contracts. The only way an athlete could change teams was to be...