Competitive balance in the CONMEBOL Libertadores group stage: evidence from 25 seasons (2000–2024)

Purpose The study investigates the competitive balance of the CONMEBOL Libertadores group stage between 2000 and 2024.Methodology The Distance to Competitive Balance (DCB) index was used to measure ex post balance using group-stage points and ex ante balance using CONMEBOL Club Ranking scores.Findings Group-stage competitive balance remained relatively stable, with no significant long-term decline and no significant difference between the pre-ranking and ranking periods. Ex ante ranking-based measures did not significantly predict ex post competitive balance. However, 49.3% of groups were outside their season-specific 95% confidence interval.Practical Implications The findings do not support immediate changes to the tournament format, but suggest that CONMEBOL should continue monitoring whether its ranking system captures current team strength.Research Contribution The study extends competitive-balance research to South America’s main continental club competition and highlights the need to adjust ex ante DCB calculations for ranking-score data.Originality This study provides longitudinal evidence on competitive balance in a continental tournament, largely absent from the literature.