Moneyball doesn't just espouse principles. It also tells a story. And that story is, well, kind of bullshit. "I wrote this book," Lewis says in the preface, "because I fell in love with a story. The story," he continues, "concerned a small group of undervalued professional baseball players and executives, many of whom had been rejected as unfit for the big leagues, who had turned themselves into one of the most successful franchises in Major League Baseball." Obviously, the question raised by this story is: How did they do it? The book's answer, which is echoed in Bennett Miller's movie: By thinking differently than other teams, relying on numbers instead of scouting, and finding unappreciated gems like Scott Hatteberg (a catcher Oakland converted into a first baseman) and Chad Bradford (a side-arming relief pitcher; he and Hatteberg each get a chapter of their own in Moneyball). Those were smart things to do. And they helped around the edges. Bradford was a solid reliever; Hatteberg acquitted himself well at first base.
But the main reason the A's were successful in the early 2000s was that four of the high draft picks they were awarded after lousy seasons in the late 1990s all turned fairly quickly into top-notch players.