The adjusted churn: an index of competitive balance for sports leagues based on changes in team standings over time

Abstract

This paper introduces an index called the adjusted churn, designed to measure competitive balance in sports leagues based on changes in team standings over time. This is a simple yet powerful index that varies between zero and one. A value of zero indicates no change in league standings from year to year and therefore minimal competitive balance. A value of one indicates the maximum possible turnover in league standings from year to year and therefore a high level of competitive balance. Application of this index to Major League Baseball suggests that there has been a significant decline in competitive balance in MLB since the 1990s with the most severe decline occurring in the American League. This index also indicates minimal competitive balance for the American League Eastern Division of MLB from 1998 to 2003