The ones that say: "I was so and so rank last season, and now I'm stuck all the way down here, matchmaking sucks and is broken!"
And the ones saying: "This person with a negative winrate was so low last season, and is now so high, matchmaking sucks and is broken!"
Pick one guys, it really can't be both.
And other than the provisional ranks and addition of iron and grandmaster, nothing has really changed. You can't blame it on role specific matchmaking, because that isn't even live here.