I have an idea for the Hero Arena that I would like to share with you:
Some players with very powerful creatures stay intentionally in lower Hero Arena leagues to get the first positions and win the best chests at the end of the season, leaving no chance to "honorable" players that have a fit and balanced level for such leagues.
To avoid this kind of abusive behaviour, I propose that each league has a power level cut: if you are on a descending position in the league, but the league below has a power cut that is below your team power level or your character level, you will stay in your current league (no descend) and win no prize at the end of the season.
What do you think? Hope you like it!