BiographyI play Sona, Singed, Vlad, Xin and Nasus. You can see that's one of each role: Support, Tank, Mid Caster, Jungler, and Solo Top.
On Twisted Treeline, I play Mundo, Nunu, Nasus and Singed.
I think your success should be measured Kills+Assists-Deaths=Score
The Sona player who goes 1-1-27 Has a Score of 27
The Yi player who goes 17-8-1 Has a Score of 10.
Players should choose their Champs accordingly, instead of just looking at kills/death ratio.