The NFL competed without a formal salary cap closing in on a decade ago after the Collective Bargaining Agreement between team owners and players, which regulated the level of the salary cap, expired. While a couple of teams would eventually be fined for abusing those circumstances, it was generally seen as something that nobody wanted repeated.
Nor was the offseason of 2011, in which the CBA did not exist. Outside of the mandated events, such as the draft, there was no offseason. Undrafted rookies were not able to sign with teams during that time, and there were no OTAs or minicamps and things of that nature.