NFL free agency can be an unforgiving place. The most promising players sign for significant, market-moving deals within 48 hours. The ones who miss out on those millions of dollars have a much harder time finding their new homes. While most of these notable players will end up securing some sort of opportunity, they'll be parachuting into an organization that isn't offering a multiyear guarantee for coaches who clearly didn't see them as an immediate priority.
Increasingly, the definition of "promising players" excludes veterans who have completed their second NFL contract (the deal a player signs after his rookie-scale contract ends).