NFL analysts often state that, on average, five NFL teams fail to return to the playoffs in a given year.  This stat also implies that five teams will make the playoffs after missing the year before, sometimes after having a weak record.

Fantasy football players spend their free team trying to find this year's sleeper, one of those players that show up out of nowhere every year.  Even average fans know of Arian Foster, Miles Austin, Alfred Morris, and the like.

These surprises are what create the amazing drama and competitive balance NFL fans have grown accustomed to.  These are the reasons behind the NFL's massive growing fan base.

2013 has been no exception, and the following are the biggest surprises of this year.