Maybe you should look at ELO again...
Its an algorithm based on your win lose ratio, Techniquly it has nothing to do with skill or champs, dispite the fact that Riot claims otherwise. The ONLY thing taken into account with the ELO system is how many nexuses blew up. The algorithm doesnt give a damn who played the match, what champs were in it, what lanes the champs were in, if they won their lane, if they won teamfights, if they took barons and dragons, what their KDA was, so on so forth.
THE ONLY THING IT TAKES INTO ACCOUNT IS WHICH NEXUS WAS DESTROYED.
Stop treating it like its anything other than that......