The aim of the thesis is basketball player analysis and determining the best way to estimate player efficency. The first part is dedicated to collecting data from three different web sites: Euroleague home page, Spanish ACB league home page and German BBL league home page. The second part describes four different metrics: Performance Index Rating (PIR), Player Efficency Rating (PER), Four Factors (FF), Wins Produced (WP) and how to compute them. The final part is dedicated to comparing these metrics on three different criteria: finding the best players in the season, performance rating changes across different seasons and win forecasting. Investigation is made about, how efficency estimates change when basketball players play in different leagues.