Roster turnover is an accepted fact of NFL business and the team-building process. And today, the process has never been more team-friendly. With the NFL salary cap set to approach the $200 million mark in 2020, player salaries and annual cap hits are not going to stop expanding relative to the cap, but under the current collective bargaining agreement, teams still have ample flexibility in the amount of guaranteed money they desire to offer and the structure with which it can be distributed.
The financial advantage of the NFL Draft is a big part of this as well.