The NFL salary cap is the proverbial boogeyman in the league; it isn't real, but it can be if you make it that way. To make it real, you have to make some mistakes, such as overspending and issuing bad contracts. We see it every year where teams will overspend or overcommit to players and quickly regret it.
Recently, Bleacher Report's Gary Davenport wrote up the most overpaid players in the NFL by position. Nowhere within it were the Minnesota Vikings and any of the contracts they have awarded their players or free agents in recent years.