I think it is important to note that the culture (or a cult of Personality) of the teams as well. As all of the top three teams have a very specific person/dogma dictating the culture, i.e. the New England has the Brady/Belichick combo, Seattle has their “Legion of Boom”, and Denver has John Elway as their philosophical North Star.

Each of those three teams have an established culture and it helps that any new player that comes in, is either integrated (and then flourishes) or they are removed. In the modern NFL, I believe that counteracts a lot of the turnover that is commonplace.