A lot of people watched the Kansas City Chiefs playoff loss to the Pittsburgh Steelers. Not only did you have the massive Steelers fanbase but also the prime time factor. Moving the game from noon to primetime helped.
For a reference, the Royals World Series averaged 8.6/16.
The ice storm could have created a permanent time slot on Sunday night. The NFL won't want to give up those ratings. I bet next year we have a Sunday night game. The downside is so many kids won't be hanging out with their family watching the playoff game.