most asocial players get best grades
I noticed that the players who play the most asocial get rewarded an S most often, especially in aram mode.
This game is promoted as a team sport, but in practise the ones who teamwork the least get the most rewards; the ones who last hit everyone else's kills, take all the healths, play only for their personal gain (letting own team get underfed) and in general don't give a crap about the 4 others on their team. They're not doing anything reportable but (maybe even more so cuz it isn't reportable behaviour) it is frustrating for the ones that do try to teamwork, play their best and expect the same from others in their team. And because they get rewarded they don't see that this isn't what teamwork is supposed to be about. This way, the grade system is only supporting asocial behaviour from players.