Winning consistently is tough. People don't realize that teams like the patriots are like once in a lifetime dynasties.
In recent memory, the Steelers had a two to three-year skid after their second Super Bowl, and made an appearance in the third one and lost and then had a little skid after that.
They lost to that Super Bowl to the Packers, who since then haven't enjoyed much success outside of the regular season and this year were very much exposed as being a team that relies on two players.
Recent example of being consistently good outside the patriots might be the Seahawks but won one, lost one, and time will tell if they continue to be an elite team and make the right calls and adjustments to remain near the top.
The ravens had a 6 year run of brilliance that should have resulted in two Super Bowl Appearances with a third near appearance by a rookie qb/head coach tandem. Since then the team has gone through major change and yet has only been completely out of the playoff picture by December in one year. It's been four years...I'm thinking next year might see a resurgent Ravens if the FO makes good decisions in coaching, FA and the draft. Only teams like the Ravens and Steelers can rebuild while still remaining in the picture and playing competitively.