Atlanta CSA has over 6 million people, and yet they have managed to lose not one, but two NHL teams to small markets in western Canada. People go to Hawks and Falcons games just for the air conditioning. Worst sports town in the USA
There are also accounts of the Braves pulling in three-digit attendances back in the 70's. Atlanta's WNBA team, despite regular-season success, has come close to folding a couple of times.
The city is getting MLS with effect from 2017, under same ownership as the Falcons...we'll see.