I just played a normal game with Nami and my final was 1/2/47 and I was given A+. I've read that it's based off of this metric and that, but can somebody give me the definitive formula for how these rankings given out? I know it's just normals, but I thought 1/2/47 was pretty outstanding for Nami . . . .
Unfortunately there is no definite formula. The ranking is based off the average performance people have on that champion. That implies K/D/A, cs, wards, damage, everything that could make a good performance is taken into consideration. That is why getting S+ on off role supports is so easy, because you deal more damage than you would if you played support, your kda would be better, cs would be infinitely higher, the only thing that would get a beating is the warding, but I honestly don't think it has a lot of importance in this system.
Did you take warding into account as well? Objectives? CS?
place wards in the fountain, so you can inflate your placed wards score, get some kills and don't die (at all), no way you aren't going to get S+.
