The rise and fall rival leagues offers an opportunity to test how monopsony might affect salaries

Average player salaries for the major team sports for selected years

Notes: In 1967, there were no rival leagues in baseball, football, or hockey, and the ABA was just getting started. Further, there was no free agency, and players’ unions had not yet negotiated their first agreements.
Chart: Monday Morning EconomistSource: Staudohar (1996) and Ahlburg and Dworkin (1991)Get the data