I searched through the forum a Lil bit and saw, that many are complaining about the matchmaking and wintrading, etc...
Why not introducing a 1vs1 league, with a best of 5 system.
A small arena with getting dmg at spawn when you do not get out of it after 20 seconds and the guy with the first 3 "kills" wins.
Matchmaking issues wouldn't be that hard because it does only need to check the mmr for 2 instead of 10 Player.
Wintrading would be still possible in Theory but this guy needs a big bank and not everyone is buy able.
There would be no way to get carried and the mmr would be much higher precision.
Of course not everyone likes 1vs1 and some classes are pretty awkward to play in 1vs1 (thief I believe?) but there is a good chance that people would like it and MAYBE it could help the balance team to see if a class has more Potential in curtain things than anything else, but this balance things are a big maybe.