League ranked system

The league ranked system is just a bunch of shit. I'd like to know how when i played in the ranked flex this season with the same two friends for ever game they are placed at a different rank. In these games i played as usually the best or second best player out of the three of us. Yet even though we played the same games the two of them are placed at bronze 1 and i get ass raped by league and i'm placed in bronze 4. We played the same fucking games. How can this fucking ranked system be that fucked. League get your shit together with this shit system.