Did the American Association of 1882-91 Achieve Parity with the National League? Evidence from Interleague Exhibition Games.

The article investigates whether the American Association (AA), a major baseball league from 1882 to 1891, achieved playing-field parity with the National League (NL) during their coexistence, focusing on the middle five years (1885–1889) when parity was most plausible. Analyzing over 350 preseason and postseason interleague exhibition games, including the World's Championship Series, the study finds that the AA's overall winning percentage against the NL was approximately .497, indicating near-equal competitive strength. Both leagues' mainstay clubs posted winning averages above .500 against the other league, while weaker, part-time clubs performed significantly worse, with the AA's part-timers faring poorer than the NL's. Despite on-field parity during this period, the AA's weaker leadership and management contributed to its decline and eventual absorption by the NL in 1892.