Team balancing is fine on competitive, because if your a team of 6 you get matched with another team of 6, team of 2 u get a team of 2 with any other people playing singles.
But with Quick play and arcade game mode, if you play singles you get placed with teams of 6 who just destroy you? Also with people leaving games near the end most people are likely to replace the person who just left they end up with a defeat without having the chance to pick their character.
Blizzard needs to fix these issues before they work on any other character development.