Solving the tanking (intentional) behavior shouldn't be a big fuss and should be punished by :
1- Degrading one level to make them lose -20% instead of remaining in same level to be able to add 20% more ...
2- Closure of training facilities until they promote to the above level. (Training won't add more skills to players but increase bonus only)
Anyhow
To sum up the ideas of this topic :
A- Punish careless managers + intentional tankers by degradation + the closure of training facilities
B- Reward skilled smart + rich managers by the option of skipping one/three level each month.
( ex- allow the manager who wins the league and why not the runner up the option to skip one league if he wants to )
C- Allow everybody to buy 7/8/9 stars players BEFORE THE LEAGUE DRAW through auction as long as they have enough resources ...