Abstract：Spectator attendance is a key factor and determinates a successful professional sport's development. A professional sports league focuses on a competitive balance between teams to increase the tension in order to attract bigger-crowds. However, a focal team focuses on winning every game in the competition. Thus, a paradox exists between the league and the focal team. This study aimed to explore the relationships among competitive balance, attendance, and market commonality in professional sports. To test our hypotheses, we used data from the Chinese Professional Baseball League's (CPBL) regular games from 1990 to 2011. The empirical findings showed that competitive balance significantly and positively influences the attendance at league level (focal team vs. rival team) and matchup level. Furthermore, market commonality (between focal team and rival team) significantly and positively influences the focal team's attack frequency (performance). This study advises managers of the CPBL that when arranging games, the supporters of the focal team think that the rival team is a major competitor, and vise versa (market commonality). Market commonality increases not only the performance of the focal team, but also the competitive balance. Both variables further increase the spectator attendance and thus resolve the paradox between the team and league. (Full text)