Ranked Champion Selection Idea

Since there is a problem with trolls and people that first time pick a champ in ranked why not limit the champions you can pick to those that the player has a certain level of champion mastery. I am not sure in the champ mastery level should be 4 or 5 but, I feel like this would help out with the issue. Let me know what you think.

There are other MOBAs that do a similar thing so I don't think it is that out of sorts.