In sports, as in so many walks of life, economics has a way of vindicating its status as the dismal science. That shiny new baseball stadium must be good for the economy, right? Wrong. An appearance by the local team in the World Series, that has to be a boost for businesses, no? No. Isn’t there intangible value in being a “major league” city, and having a winning team? Well, maybe  but the emphasis is on the intangible.

It’s almost impossible to find an economic study  other than those financed by stadium boosters  that shows a positive impact from taxpayer investment in professional sports. As Oakland tries to figure out how to keep the A’s and the Raiders in town, and as Santa Clara works to lure the 49ers south from San Francisco, the mountain of evidence showing that stadiums are unreliable economic engines looms large.

But if you were anywhere near AT&T Park in San Francisco last week as the Giants battled the Philadelphia Phillies for a spot in the World Series, you could only conclude: Economists are nuts.

Throngs flocked the streets around the waterfront ballpark, many walking from downtown offices. Bars and restaurants were overflowing, parking lots were charging $60 a spot and the sea of orange betrayed huge spending on apparel and souvenirs.