This is a book written by Michael Lewis published in 2003, based on Billy Beane, the General Manager of the Oakland Athletics, and a strategy he championed a new strategy evaluating baseball players. Prior to Mr. Beane's time as General Manager, players were evaluated by scouts and those scouts based their evaluations on classic statistics and what they saw. Billy Beane used new statistical evaluation tools and methods to evaluate players and constructed winning teams repeatedly. He took advantage of the other teams unwillingness to adapt to his way of evaluating players and was consistently able to sign the players he wanted.
The book Moneyball was eventually made into a movie released in September of 2011. Since the publishing of the book, most every team in baseball has begun using similar methods to evaluate players. In fact, the book influenced many other sports as well as interest in evaluating players using more advanced methods. This was partially helped by the advent of the internet and the available computing power and space to store all the necessary data and access it quickly.