It has been said before, and I'm saying it again. New champions should NOT be selectable in ranked
They should be banned for a week minimum but honestly two weeks is the best option.
Patches come out every two weeks, so if there is a game breaking bug involving the new champion, or there is a high skill cap, or the champion is overtuned, or overpowered, or even underpowered, the dev team has a chance to fix it BEFORE it starts affecting peoples ranked games.
I don't want Sett on the enemy team. Why? Cause my top laner has no idea how to fight him and will feed him, and then the 12/0 Sett will destroy my team.
Guess what? I ALSO don't want Sett on MY team. Why? Because my top laner hasn't played him before and will feed.
If my top laner wants Sett and I ban him anyways? They dodge.
Riot continuously releases new champions without any exact knowledge on how this champion will affect the meta, which champions will counter them, which champions THEY will counter, optimal build-paths for or against them and yet they expect US to be able to do the same. It's flat out not right and just like so many other features that has come to League (5 bans per team, bans distributed across the team, replay function, custom training tool, etc) it makes me wonder why/how it takes so long to do something like this.
Riot has actively banned champions before, weather it was for game breaking bugs, being overpowered, or simply because they wanted to promote an event that was currently on going (cough cough
cough cough). So simply banning champions in ranked because they are new and Riot has only the roughest idea on how powerful the new champion would be seems both easy to do and great for the player experience.
If you don't agree with me on this because I am using Sett as an example, just replace Sett with Aphelios....yeah