I was going to ask if Platinum was dead or a game glitch happened, or perhaps a bunch of hacked accounts were found.
I noticed I had >1000 place rank, on my dying deck, which was weird, as I had no idea that is even mathematically possible. So I started a new deck and was immediately placed around 116th rank. I checked the leaders-list and in the 400-500 rank are decks over 200 days old.