This post is really for what happened to my friend but just happened to me as well just now!, i went 17-0-10 as Warwick and got an A+. I don't known if creep score is a big change for grading but i find an A+ for that score kinda aggravating. Sorry just heated :D
Zero transparency from Rito on the grading system because they were to stupid and made it easily exploitable..
So you can go 9/0/4 Zyra and get an A or 13/2/8 Tristana and get an A-
well cs is a big part and blind pick is easy to cheese by playing a support champ as a carry because it doesn't take into account which lane you are in it just counts what the champs primary role is ive been playing ap rakan mid and I got 8 s+ in a single day I might have over 100k mastery but that's a bit much don't you think
Grading is determined by comparing your entire kda including cs with the time to other records of that champion. If the game was a complete stomp in 20~ minutes then you can reason that other 20~ minute games must also be a stomp. In that case then, it's how well you played compared to how well others played that same champ.
With that being said, the reason you didn't get an S or higher is most likely due to your CS and kill participation. You did well just not as well as other players have done in that same time frame.
