After having been plagued with AFKs in my ranked games (Bronze... *sighs*), I think that harsher punishments are needed for those who AFK in ranked.
If someone goes AFK in a normal game, a leaver buster penalty is a good and fair punishment. However, in ranked, someone going AFK because "they've had enough" could cost someone their promotional series.
I think that maybe something like a 2 or 3 day ban from ranked would be a better punishment, and would also act as a deterrent for people who may go AFK.
Thanks, Only Welsh