There has to be a solid wage floor, at the very least. This could create new problems, too. There are eleven players on the field at any given time. How much of each player's performance is down to them, at an individual level? How does one measure the performance of players in positions that don't create a lot of statistics? How does this guarantee better overall team play and not create individualistic divisions within the team? Team-based performance incentives might be better. But, this could create new tensions in the locker room and could place managers into an even trickier position vis-a-vis players and place them under even more scrutiny than they are already under.
I think the best thing would be for football to regulate agents and the perverse incentive structure they have. So much of what goes on has to do with agents trying to cash in and make huge profits off of player sales. It keeps players' heads turned and sucks up so much overhead cost from clubs and players alike. Something could be done about this.