Could Vikings' guarantee for Cousins start an NFL trend?

The idea began to percolate about 2½ years ago, in discussions between Kirk Cousins and agent Mike McCartney about his status with the Washington Redskins and his future in the NFL. The goal was to get a fully guaranteed contract, the security players in this league of high turnover and short shelf lives have sought for decades, unlike their peers in professional baseball, basketball and hockey who are accustomed to guaranteed money. This week, when Cousins finally reached free agency after two consecutive seasons playing on the franchise tag, the Minnesota Vikings made that once-unrealistic aspiration happen with an $84 million, three-year deal.