Oh, yeah, the famous rigged HS matchmaking. 
What is ‘MMR’ anyway?
See above re Elo rating… Perhaps I could elaborate on that some more: the chance of Bob winning against Alice is quite reasonably predicted by the difference in their Elo ratings. In a game of HS, putting the unknown rigging factor aside, the chance of a rank 1 legend player winning against a Bronze 10 player is 50% plus-minus a vanishing epsilon.
Ha! Quite the opposite, considering, for instance, the abundance of bots, including obviously dumb and crude ones, throughout all these years (there’ve also been season beginnings, by the way). I’ve posted this a couple of times as a characteristic illustration of the role of skill, but perhaps I’ll do it once more:
So yeah, to make this post not so off-topic, I’ll list this particular target here: finding that prominent role of skill in this game.