First of all, this thread is about playing in a Cup with teams of your level or maybe 1 lv less - as a start for going for the treble.
League draw has a different logic. Two previous seasons I was starting the season with 14 players (8 6* players and 6 1* players), I had an easy draw in the Cup but still I was playing in a league full of teams with 5*-6* players. I won the treble but it was tough. So, dropping the quality doesn't secure that you 'll have an easy league. There are other factors about that.
* may opinion (but not sure) about that is that the system also counts how active you are, if watching games, if buying and sell players, how many titles you have and maybe this fb app where you can see the rank you have as a manager in t11.
So, if still you want an easy Cup draw, you must keep 8 good player and buy 6 low q players, so it would be 3*. You should keep the three 7* players + five of your 6* players. Then buy six 3* players. It's difficult to do this in the rest of the season, so I suggest to keep that plan in mind for the next season (and start selling few days before). Today & tomorrow, Try to sell 2-3 players (at least) and find 2-3 3* players (not old fa because the will retire). Also keep those 0T 2* academy players of the next season.