Introduction: Research has been conducted on the relation between salary and efficiency of professional sports players in order to investigate whether or not acquiring a multi-year contract causes less effort paid in post-contract seasons. With progressive development of professional baseball in Taiwan, the relationship between players and league clubs has gradually changed in terms of contract types: from one-year contracts to multi-year contracts. Based on multi-year contracts, players attain better salaries and welfares while league clubs attract more valuable players. As multi-year contracts are getting more common in Chinese Professional Baseball League (CPBL), it should be carefully evaluated that the performance of players is worthy of their salaries. Methods: This study is going to evaluate the efficiency of 10 pitchers and 13 batters with multi-year contracts during seasons from 2004 to 2016 in CPBL. First, with Data Envelopment Analysis (DEA), the efficiency of players are evaluated by setting appropriate input and output variables. Then the players’ efficiency are analyzed in terms of before and after the contract signing with bootstrap. Furthermore, Multiple Regression Analysis is used to determine which factors affect the contracts length and salary and to reach a possible balance between players and club leagues. Results: The empirical results show that, for CPBL fielders and pitchers, there are no significant differences with respect to the Constant Returns to Scale (CRS), Variable Returns to Scale (VRS) and Scale Efficiency (SE). Multiple Regression represents that the salary and length of the contract are with low relevance to the batters efficiency. The tenure and winning percentage of the pitchers have a direct impact on the contract’s salary and total salary, fielder’s contract length and age have a positive effect on the contract’s salary. After the standardized Consumer Price Index (CPI) calculation, a player salary is recessed. Conclusion: The efficiency of CPBL players is not effected by multi-year contract signing. It is recommended that league clubs by signing multi-year contracts ensure players with better salary.