You have to know AT LEAST 2 roles before you play ranked.
I was just recently in a game playing darius top. I was doing well until my jungler took 2 tower shots and gave a kill away to the other top laner. I asked what was up, why'd he do that? He said it was because he only plays support and cant play jungle or any other role. He then continued to go 0-6 and we lost the game before 20 minutes.
I have never made a discussion on the League boards, but I'm hoping at least some people read this. Is there a way to enforce all players to learn more than one role or at least not queue up in ranked if they can't? Please give me feedback, thanks!