My suggestion would be to put all players back on roster.
Freeze the roster
take his avg weekly points and make who ever that team plays over the last few weeks at least have to beat that.
I know that leaves a lot of grey area but after week 10 ,I think we should have a pretty good avg.
put something like that in stone and at least the rest of us will know the rules and have everybody play by them.
Any team involved (with dropping excessive players)can not be eligible for any prizes.
That would keep anybody with a good team trying to find a loop hole

(because you know it would happen)