End of match grading system broken?
I am currently grinding S grades to get miss fortune to mastery rank 7, and in this game (see screenshot), i was 8/1/1 in 10 minutes and fed through the whole game, i ended with getting 25/6/10 and i got an A+? While a yasuo who was 2/8 until the end of the game, got an S after afk farming alone and not contributing to the team at all, like wot? Rek sai also got an S, with less gold and assists than me.
What the f*ck is the grades based on?