Leagues matchmaking is somehow even more screwed up!

I am a bronze 4 player and play regularly normal games and not much ranked. But recently I encountered a player of much higher skill in a norms game while playing with my lvl 19 friend, this player we found was diamond 5 and not believed to be duoed with anyone on the enemy team. This player was playing Camille as seen here http://imgur.com/cjTMqY2 I would like to ask any of you why you belive this happened and i would like to ask riot the same question.

P.S. Don't flame the person that was in the game they had no control this is not to everyone just the people who don't understand this please say something if you have had a similar experience if you would like to it would be interesting thank you. http://imgur.com/aCNSsrb