Recent patch for the PC version disabled the "Avoid this player" feature since it was causing problems with the game's matchmaking system. Apparently people were abusing the system to avoid playing against skilled players instead of the idea of it being used more against griefers or cheaters.
https://www.destructoid.com/blizzard...e-370317.phtml
Blizzard is also going after those who quit matches for the game's competitive mode with bans among the punishment options being issued. Same 75% EXP penalty as leaving matches in Quick Play mode but with the added kicker of being suspended for a series of matches or banned for the current season.
http://beta.egmnow.com/articles/news...sult-in-a-ban/