Many people read Michael Lewis' terrific book, Moneyball, and they concluded that it was all about on base percentage and Billy Beane's use of new statistical methods to evaluate performance. However, the big idea is really about capitalizing on market inefficiencies (which are driven by various biases).
Recently, Sports Illustrated writers described the resurgence of the stolen base in baseball. Even Billy Beane's Oakland A's are stealing bases! What's happening? After all, Beane and other statistically-minded general managers tended to despise the stolen base a decade ago. They argued that stolen base attempts often decreased a team's chances of scoring runs, unless the success rate was exceptionally high.
The difference is that conditions have changed. With steroid testing decreasing batting averages and home runs, teams have to find other ways to score runs. Speed became an undervalued asset that low budget teams such as Oakland could acquire. The lesson here is that markets are dynamic. As people become aware of inefficiencies, the opportunity to take advantage of them dissipates. Thus, you have to stay one step ahead of others who are acquiring assets. You have to recognize what is no longer undervalued, and identify what is currently undervalued.