Require a champion to be Mastery level 3 for ranked.
I got this idea by reading post that are saying that new champions should be disabled for a few weeks in ranked. But I thought, if this is to prevent people from playing new champions in ranked, why is this different then other champions?
In the past, I have had people play champions for the very first time in ranked. There are very few times I have seen them win lane or even use their kit properly. For example: back when I was a Miss Fortune main, I've supported Miss Fortunes who I knew were not experience with her hit. They never harassed with her Q and constantly spammed her E, forcing them recall many times vs. our lane opponents.
I feel like a champion should be required to be mastery level 3, or have an allotted amount of games played on them in a normal game, before they are allowed in the ranked queue.