Mastery System - Riot Please Explain
My friend and I just played a duo queue game and he just went 10/3/20 with 97 cs as a Jungler in a 31:21 minute game and he Received an A, this is not the first time this has happened to him (similar score lines and still no any sort of S rank). Can you explain how the rating system works? Because he feels kinda bummed every time where he plays amazingly and all he gets is an A.