guys, calm down. this has one major issue.
if you will decrease level of your team at the end of the season and your team will be weak at the begining of the next, you will end up in the league which will already contain couple of strong players with scouts and after upgrading the team you will be just one of them and you will face an issues to win your league/qualify to cl.
If your team will be strong at the end of the season you will start the next one as one or the strongest player. so question is, is your cup worth to sacrify league position for it ?