Poor Atlanta, screwed by the NFL rule that when a team is playing at home, there can be no other game on local tv at that time.
Because of that rule each network has to have at least one game in each time slot, even if they don't have the doubleheader that week. That is so each network can broadcast at least one game in every market every week.
Due to the home-team blackout rule outlined above, the Baltimore, Buffalo, Cincinnati, Cleveland, Tennessee and St. Louis tv markets needed a late game on FOX. Those six teams are playing at home on CBS, so there could be no early FOX game to compete for viewers.
Arizona at Atlanta became the sacrificial late game on FOX since the Cardinals are a western team, so those six markets above get shown that game to give FOX something in those areas.
And since Atlanta is the home team ... voilà, no competing game on tv for people living there.