Sports economist Phil Miller at the Market Power blog helps with the answer:
Fortunately, the Atlanta Journal Constitution presents an article in which sports economists discuss some hard data.So is the stadium worth it? No.
A new open-air stadium downtown for the Atlanta Falcons would be of enormous benefit — to the Atlanta Falcons. Neither local taxpayers nor the region’s economy is likely to accrue much advantage from a new arena built on public land, in part with public money, experts told The Atlanta Journal-Constitution last week.
“Economists have studied the economic impact of stadiums to death, and the clear consensus is that there is no positive impact,” said author and sports economist J.C. Bradbury of Kennesaw State University. “Economists don’t agree on a lot, but right wing, left wing, they all agree on that.” (Emphasis added)