Disagree.
Hawks: don't sell out, even playoff games
Flames, Thrashers: moved
Braves: lots of empty seats despite success, and playoff games have tons of away fans
I have gone to the Saints game here for 9 years. Always at least a couple thousand Saints fans there, although that number has dropped as the Falcons season ticket number has risen. A lot of fans in my section are transplants who cheer for the Falcons except when they play the Saints.
Atlanta epitomizes fairweather-fan-ness

I am a season ticket holder for both Atl & NO. I get 3 emails a week from the Falcons about ticket availabilty. I get one letter a year from the Saints, which basically says there are NO extra seats available, for any game.

Excuse me, gentleman ... if I may interject, but I need to award a point here ... "game. set. match." - ScottF.