The main theme of Moneyball is the advantage of using statistics in baseball to analyze players and teams. The entire approach of the Oakland A’s under Billy Beane is based on this statistical analysis. The author doesn’t just cover the use of statistics but emphasizes their proper use—that is, statistics that are accurate and meaningful versus those that are not. Lewis attempts to show, through this one team’s 2002 season, how statistical analysis transformed the game of baseball. He depicts a direct through line from the revolutionary work Bill James did in the 1970s and 1980s to its application in the early 2000s by Beane to the Oakland A’s.

It certainly was a revolution in thinking, as Lewis shows in Chapter 4. Baseball statistics had not changed much since the 19th century. Errors, for example, were introduced in the 1850s, when the game was played under very different conditions. They didn’t tell you much, either—as James noted that “the easiest way not to make an error was to be too slow to reach the ball in the first place” (67). By committing an error, a player showed that he actually did something right by being the correct spot to field the ball.