Totally agree with Cracicot, there is no issue at all to fix. The system works as it is intended.

The cup links together people of fairly similar quality at the beginning of the season. Obviously as the season progresses, certain levels are able to get players of higher quality than others are able to. But that's unavoidable.

Your bought superior quality team that you have will get you an advantage in your league and in the CL. The cup is where you face equal quality teams (at least initially).
You are actually specifically complaining that your opponents in the cup have similar or (some) slightly higher quality. Are you for real? Wake up and enjoy having competition and using tactics to outwit your opponents (or the troll engine) in ONE out of 3 competitions. You can buy your way to the title and champion's league in the other 2 competitions no problem.