Based on the true story of Billy Beane - once a would-be baseball superstar who, stung by the failure to live up to expectations on the field, turned his fiercely competitive nature to management. Heading into the 2002 season, Billy faces a dismal situation: his small-market Oakland A's have lost their star players (again) to big market clubs (and their enormous salaries) and is left to rebuild his team and compete with a third of their payroll. Driven to win, Billy takes on the system by challenging the fundamental tenants of the game. He looks outside of baseball, to the dismissed theories of Bill James, and hires Peter Brand, a brainy, number-crunching, Yale-educated economist. Together they take on conventional wisdom with a willingness to reexamine everything and armed with computer driven statistical analysis long ignored by the baseball establishment. They reach imagination-defying conclusions and go after players overlooked and dismissed by the rest of baseball for being too odd, too old, too injured or too much trouble, but who all have key skills that are universally undervalued. As Billy and Peter forge forward, their new methods and roster of misfits rile the old guard, the media, the fans, and their own field manager, who refuses to cooperate. Ultimately this experiment will lead not only to a change in the way the game is played, but to an outcome that would leave Billy with a new understanding that transcends the game and delivers him to a new place.

Despite having the lowest payroll in major league baseball, the 2002 Oakland Athletics were led to an excellent season by general manager Billy Beane, who upset traditionalists by using statistics and mathematical analysis in player evaluation.