Just trying to make a point that mm is unbalanced and not only because OP tanks in one team.
In my last 100 battles I played:
11 Tier 5 games
32 Tier 6 games
2 Tier 7 games
34 Tier 8 games
16 Tier 9 games
5 Tier 10 games.
From these 100 games,in:
24 games I played against +2 tier(eg.:i was in tier 6 ,top enemy player in tier 8)
36 games +1tier(my mistake,this includes +1-1 mm,and +1 only too)
27 games only in my tier
11 games where I was 1 tier bigger than enemy bottom player(me in 6, enemy lowest 5)
ONLY 2 games as top player(2 tiers bigger than enemy bottom player)
In my opinion the problem is in the balance of +2/-2 matchmaking .I had to play 12x more games against 2 tier bigger enemies than against 2tier smaller enemies. It can be bad luck but holy shit !
The worst part is that those 2 games where I was on top ,one of them was in tier 9 the other one in tier 10.
My writing is shit,but I think you can get the point and I think this is ridiculous.