We all know that players manipulate cups, but that isn't the main problem, the main problem is when there is a difference of 3 levels between managers and these managers go to transfers to rebuild/reinforce the team. For example, the manager in level 17 can buy players with 3 more stars than the manager in level 14, because the market has a limit of 5* players.
In the level 17 the "garbage" players from the market are 5* in the level 14 market. The 5* or 4* or 3* players from the level 17 market cant be bought by the level 14.
There is a huge gape of power.