本研究以資料包絡分析法來衡量職業球員的績效表現，球員在簽訂複數年合約前後與績效表現之關聯性，來探討球員是否有合約週期的現象，進而再探究球員處於合約年的比率多寡，是否會對球隊的勝率造成影響。 　　本研究以2002年球季結束後至2008年球季開始前，這段期間曾與球團簽訂複數年合約的美國大聯盟球員為研究對象。實證結果顯示投手在簽訂複數年合約前一年，純粹技術效率有明顯增加，野手部分則顯示在簽約前兩年整體技術效率呈現顯著增加。研究結果顯示支持合約週期理論，即球員在合約年之前會刻意增加表現，以便爭取較佳之合約。另外，以2009年各球隊的勝場數為研究對象，實證結果顯示，當球隊中有較多投手處於複數年合約的第一年，則球隊的勝場數顯著較少。 / This research applies Data envelopment analysis to examine the performance of Major League Baseball (MLB) players before and after signing multi-year contracts. The research also aims to explore the claim of contract cycle theory by investigating whether contract status has an influence on wining ratio of a team. The sample includes players who signed multi-year contracts between end of season 2002 and prior season 2008. The result illustrates that pitchers’pure technical efficiency increase significantly before signing the contract and fielders’total technical efficiency increase significantly 2 years before the contract signing. The results support the contract cycle theory that players show a tendency to improve their performance prior to signing a contract in order to earn a better contract. In addition, the teams with more players who are in their first year of multi-year contract have a significantly less number of wining ratio.