Better MMR formula

Except this doesn't take into consideration that you're not always facing a perfect matchup. More games are played between teams of different average MMRs than are played with equal average MMRs. If you win against a team with an average MMR 100+ higher than yours, you shouldn't be earning the same MMR increase as when you win against a team with an average MMR 100+ lower than yours.

If you keep getting lucky enough to have the higher MMR team, you shouldn't be gaining MMR at a linear rate.