Silly Billy Beane told everyone his secret.

It is rare for a sports movie to be something more than a gritty underdog team or underdog person, who, against all odds, in the final seconds of the contest, wins the race or game or series, righteously defeating, by way of homespun character and hard work, the arrogant, rich, privileged star or team or league. That’s it.

Very few sports movies get outside that box. Field of Dreams, Murderball, and Eight Men Out come to mind.

A candidate for this select brotherhood opens Friday: Moneyball, directed by Bennett Miller (Capote), screenplay by Aaron Sorkin (The Social Network) and two other writers (see next paragraph), plus the usual scrum of producers and corporations. The film stars Brad Pitt as Oakland A’s general manager Billy Beane, Jonah Hill (the fat sidekick in Superbad) as sabermetric geek Peter Brand, and Philip Seymour Hoffman as Oakland A’s manager Art Howe. In terms of the cast, Hoffman doesn’t know how to give a bad performance, Pitt is A-list, and early reviews say Hill is fantastic. The film is based on the best-selling book by Michael Lewis, Moneyball: The Art of Winning an Unfair Game. Lewis sat in on the team throughout the 2002 season.

Moneyball is an interesting movie on several levels, aside from the unavoidable sports-movie element of “tenacious underdog makes good.” It’s interesting because of the difficulties getting it made (three writers, three directors, Sony shut down production three days before shooting was scheduled to begin, to be followed by reshuffle and resurrection, not a sure thing at the time). And it’s interesting because it’s based on a book that is, at its core, a business book, to wit: how to find value in a gaggle of seemingly below-average baseball players, players who were overlooked or discarded by the rest of the league. Which brings us to OPS (on-base plus slugging percentage), a sabermetric statistic that measures a player’s ability to get on base and hit for power.

The movie is about back office, chair-sitting, baseball executives. The game of baseball is backdrop; the stars are the general manager and his sabermetric sidekick. Here’s the plot: two baseball executives use statistical analysis to field a winning team.

Not a grabber...in fact, this may be the first statistical analysis Hollywood movie. Mathematics as plot point. Saying that, I predict this film will do boffo box office. What can I say, I’m a sucker for movies that put equations up on the big screen.

The star of the book and movie is Billy Beane, Oakland A’s general manager. Oakland’s 2002 team payroll (the year Lewis spent with them) was $40 million, the 28th lowest payroll of 30 major league ball clubs. Sure, the film has a few small cheats — hey, it’s a movie, not a graduate thesis. It’s true, the A’s were a small-market team in 2002, and it’s true they lost Jason Giambi, Johnny Damon, and Jason Isringhausen to rich teams after the 2001 season. But, they kept the 2002 American League MVP (Miguel Tejada) and three of the best pitchers in baseball: Barry Zito, Tim Hudson, and Mark Mulder. Also, the A’s made the playoffs the previous year, 2001, and the year before that. It’s not like they were street urchins who had never known what a hot meal tasted like.

The irony of the story is not that a small-market team with a budget less than one-third the size of the Yankees made it to the postseason, but what happened afterward. Specifically, what did those big rich teams (read, Boston Red Sox) do? Clue: the A’s haven’t been to the playoffs in the past five years, yet the film’s star character is still the general manager of the Oakland A’s. What happened? The book’s author, Michael Lewis, explains. Follows is from a recent interview with Susan Slusser, a San Francisco Chronicle staff writer.

“What ended up happening is no surprise. When someone at the top of the food chain like Boston starts operating like a small-market team, it puts order back in the universe. From the top, there were significant adjustments that had a huge impact all the way down. We knew that was going to happen and that the smaller market teams would be fighting uphill.

“The market inefficiencies have been corrected. Everyone is operating with the same information, and the opportunity to be smarter than everyone else isn’t there. That dooms the A’s. I’d really be shocked if they are able to get back into the playoffs in that stadium, with those revenues....”

Got an appetite for good movies? The San Diego Film Festival kicks-off September 28. Hie thee to sdff.org for particulars.