players and team distibution is solo/duo ranked

I just had the most miserable experience in ranked game I am silver 2 i was gold 5 before season's ending. Anyway, the last game i played in ranked queue was a but 10 mins ago and i had a top lane lux who is obviously trolling from her pick, she didn't even go top she went bot and fed the whole enemy team, the only item that she got was Bf sword... and the end i realise that she is not even in a league... thats her first ranked game from like a while i guess .... idk what the hell is happening with this game... How just tell me how an unranked player is playing in my team ...