In the parity-driven NFL, about half the playoff teams churn every year. This means that some of last year's much-hyped playoff teams are in for a rude awakening in 2015.
Since the league moved to a 12-team playoff format in 1990, an average of about six new teams made the playoffs every year. Only twice, in 1994 and 2012, did that number dip to four teams. This long history of churn among NFL teams means that it's highly probable that five or six teams that did not make the playoffs in 2014 will make the playoffs in 2015.