The Leagues are based vaguely on quality after friends are grouped together. There has to be some variety though. I do not have friends on my level now, and my league consists of teams pretty near in Q, with some better and a couple worse. This late in the season there will be greater gaps depending on how active the managers are.

I've heard more complaints of it being all the same Q rather than otherwise.

If you feel your league isn't hard enough befriend strong teams on your level.

Having a 5* or better average (top 14) is asking for a hard Cup, by the way, since it is based purely on Quality, you will likely face teams a level or more above you.