there should be more criteria that determine if you are ready for ranked
i know for a fact when I first went into ranked I wasn't ready, I went 2/8 in promos and fed so hard that it could honestly be seen as inting, and I just had someone on my team who had less than 200 games played TOTAL in pvp ruin what would've been an ez game. it would also discourage smurfs, which IIRC riot has stated they want to do