Over the last few regular seasons and Superbowls, it has become apparent that the referees are pretty bad when it counts (especially when helping the Steelers' win). At this point you would think the NFL would do something about it.
The NFL is the most valuable sports organization in the nation. More valuable the MLB. Baseball has MLB employed umpires and an umpiring school for them to go through as well as minor leagues for them to umpire in first to rate them. MLB umpires do make mistakes occasionally still but not normally game changing mistakes, especially now with instant replay for home runs / foul balls. Of course, one play or pitch in baseball isn't as important as one football play either.