little bro just went 10/3/10 229 CS 15K gold~ 
gets S-
his jungler 
10/1/12 13K gold~ gets S or S+? couldnt remember which one. i would assume it's an S
in a 30min game. 30:18 if u wanted to be precise.
i would assume the Yasuo got an S- or something off this match too, didnt get a chance to see his post-game lobby.
how the actual [insert rage] is your grading system working Riot?! do we need to hit 20 kills and 500cs by 20mins just to get a B?!
It gets compared to every other player of that champion in that role at that skill level
The system is comparing a player's performance using a champion in a role/position with other players' performance using the same champion in the same role and position. If the best of the best is getting 500 CS then if you want the same grade as them you better be getting just as much in addition to showing similar results in every other stat.
So basically the reason that players sometimes get S rank even though they were absolutely horrible is just because in that particular comparison EVERYONE was playing that champion like Dirt V?
