When you fall to rank 5 or loose more than once in a roll you tend to get a good matchup. Note that getting a bad matchup or mirror doesn’t mean you’ll loose. It just takes a lot more to win. And if you keep winning you’ll tend to match with counter decks until you loose or reach legend.
Note that some decks don’t really have a hard counter, so you can win vs those counter decks if they don’t draw their tech.
For example how often does a tempo oriented secret mage run 2 ice blocks. Imo that is a unicorn type. But a lot of the secret mages my mozaki faces for some reason have them like 66+ % of the time. Or mirror with another mozaki with secret eater for some reason.
Naturally when I switch to secret mage then ice block doesn’t exist in tempo secret mages 100% of the time.(mine doesn’t have it either since it’s not a tempo oriented card).
If you check one of Zeddy’s videos with a title " The Biggest MYTHS and CONSPIRACY THEORIES in Hearthstone!" And check the comment sections you can see just how many players are convinced of the rigged matchmaking (it’s a lot).