Just finished a game before the maintenance and I am super confused about my mastery score and grade that I got. Maybe this could be a bug, not sure though, maybe I am just bad.
I was playing Zyra mid. My KDA was 10/1/11, I had placed the most wards on our team (2nd most in the game). I did the most damage to the champions.
I got grade **A** and only **289** mastery points. That doesn't look accurate, huh? The only stat that is really bad is CS. Maybe cs has too much influence for ranking? When I played support I never had this problem and I got S grades easily with Zyra.
As you can see in the screenshot our Yasuo got S, while having same kill participation (21 out of 31), more deaths, lower damage to champions, higher damage overall, more cs, less wards placed.
If cs is not the problem, then you are telling me that average Zyra mid on PBE is getting 30+ kills per game and doing just more than I did? :|