I would like to propose an auto-ban system for leavers in HLW for the following reasons (spoilers are for people that may not be as familiar with HLW or my explanations):
1) Really hard late game if teams are initially balanced (2v2, 3v3, 4v4) (some people are reluctant to start the game unless teams have an equal number of players)
Spoiler!
2) Leaving mid tier-1, tier-2, or early tier-3 can cause a leveling imbalance
Spoiler!
If you have any questions, please feel free to ask me.
Cheers,
Amnon