Why Is Yuumi In Ranked?

Wouldn't it be a better experience for all involved if a new champion was not put into ranked right away? Why not have it be normal only for a patch before introducing to ranked? This would give people a chance to still learn the champ (in an environment where it encourages new champions) and it will protect a team from losing just because a champion is picked.

I went from maintaining a 65% winrate over last 40 ranked games to suddenly being 0-3 with this champ on my team. I want to use my ban to ban Yuumi just so it doesn't end up on my team.