Response to AW updates
There are a couple of things that should be discussed:
1. The reason there isn't great defender and attacker diversity is because of the dearth of champs that are useful. There are a great number of champs that serve no purpose outside of defender diversity. Real solution is to make better champs or update current terrible ones. You have taken great pains to nerf former popular characters (Dr. Strange for example went from hero to zero), or put multiple counters against formerly good characters (Quake, can't risk her against a tech or mutant and she is not good on stun immune nodes to start with). Part of the problem is in development. The number of terrible champs no one ever wants to rank up is at least 3 times bigger than good champs. Off the top of my head useless champs: Sentry (prestige and that's it), Karmala Khan, She-Hulk, Hulkbuster (most of the iron family for that matter), Groot (he even sucks for arena), Iron Fist, blackbolt, Gambit, Phoenix, Howard the Duck, Lady Thor is terrible, etc
2. When you change the meta of the game rank down tickets are an automatic discussion topic. No way around it. This appears to be changing.
3. Matchmaking has multiple ways to make it better but you set up the system so that the best teams can drop to the bottom by virtue of only matching good teams and bad teams can creep up matching only bad teams. High AW rating is a detriment to success. The top is likely to try to avoid each other in that context. Maybe you don't watch competitive sports but in NCAA football. The top 12 teams don't all just play each other all season then have a team from say the MAC get to play for the championship by going undefeated.
4. If you want to avoid certain problems I strongly recommend you expand master to the top 35 (like AQ top tier used to be) or say top 30. Sliding a few more teams in gets rid of some of the motivation to cheat.
5. As far as cheating goes it's simple. Losing to a team that got caught cheating amounts to a win for the losing team. One team gets docked, the other rewarded.