觀眾人數是職業運動發展中最重要的關鍵因素，聯盟強調所有隊伍整體競爭平衡增加比賽張力以吸引觀眾；然而，各隊尋求每次對戰中獲勝。二者間存在利益衝突的矛盾。本研究目的在探討競爭平衡對於觀眾人數的影響以及市場共同性對於焦點球隊比賽表現的影響，以中華職棒大聯盟1990年至2011年例行賽資料進行實證，研究結果顯示：無論是聯盟層次還是對戰組合層次，競爭平衡對於觀眾人數皆有正向顯著的影響；對戰對象與焦點球隊的市場共同性，對於焦點球隊的攻擊量亦有正向的影響。因此，本研究結論：本研究之意涵為市場共同性有助提升球隊比賽表現，進一步提升聯盟競爭平衡進而帶動觀眾人數，解決各球隊尋求對戰獲勝與整體競爭平衡間的矛盾。

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.