Buy a 3 star player, bankrupt the club to train him to 7 stars. Up sell. Rinse and repeat. The age of the mutants.
Up selling hasn't been addressed in the latest update, so it must be ok. Once the training restrictions have been figured out up selling will continue with players who have 340% in ALL skills.
Too much money to be made to stop up selling. How many rest pack/tokens get spent to move a player up the ladder constantly increasing quality?