How the hell do you get an S rank?
Okay, this has been driving me nuts for a while now. How the hell do you get an S rank?
http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2446035276/40146362?tab=overview
Second most kills in the game behind only the 27 kill adc. Least deaths. Tied for third overall on assists. Most wards dropped on my team, second most wards overall. Second most damage on my team, third most overall. Every dragon secured except one. While I don't claim that all my games go so well, as far as I can gather I did everything in this one right. Lots of fight participation, most kill participation outside of the super fed adc, objectives and map control, the only thing I could've probably done better was farm, because I put it off in favour of running across the map to try and help my team. Overall one of my best games in a long ass time...
And yet it was only an A. Even more infuriating is that I've gotten S ranks on other champs with drastically worse performances.
So what the hell am I misunderstanding about how grading is done?