Even once the ligament has fully recovered, the muscles surrounding the joint have to also be re-conditioned to bear the player's weight. That's typically the hardest part of the recovery, especially since muscle-memory plays such a huge part in football.
May cost a few more $$ but I will highly assume the coaches pretty well have an idea of the shape of their team before this final cut day. It does however give these fringe guys a little bit more time to have a few "wow" film episodes or ability to show they are getting it down but was slower that the last guy to pick it up. It's a good start