Free agency helps shape teams in a major way in terms of how good they will be in the upcoming season. Adding veterans at positions of need is very helpful for teams that are a piece or two away from truly contending, or for organizations that do not want to go into the draft with one arm behind their back and be forced to draft for need instead of value.
The Dallas Cowboys have seen some of their free agents walk out of town: Byron Jones to the Dolphins hurts the secondary, Robert Quinn to the Bears hits the defensive line, while the Raiders added a boatload of former Cowboys such as Maliek Collins, Jason Witten, and Jeff Heath.