The NFL sells the idea of parity and brings facts to back it up. In 15 of the last 16 seasons, at least one team has won its division after finishing last or tied for last the year before. Each year since 1990, a span of 29 years, at least four new teams have qualified for the playoffs. There were eight new qualifiers in 2017 and seven this season. That’s a great way to sell hope, but that turnover is precisely why the biggest obstacle is remaining competitive.