A perplexing case: How is it possible a player drops 1000 mmr from the immortal bracket?

Observe this interesting case:

For the last few months I have hovered around Divine 4 – Immortal.

Suddenly after the new behavior score system dropped, I will admit my behavior score tanked likely because of being annoyed with non-stop hispanics on my team in US servers or annoying griefers or whatever- point is I lost a ton of behavior score. I get that and accept that.

However – the insane part is how over the next few weeks, due to somehow insanely unwinnable game percentages with unplayable teams, my mmr has dropped ONE THOUSAND, leaving me around Ancient 3 today.

Ask yourself, scientifically, what possible circumstances could even cause a Divine 4 level player to drop such massive amounts of mmr so fast?

Literally the only thing possible if that person sold their account, or they just literally rage fed every game or something (im not doing that).

The only logical explanation is that due the matchmaking algorithm surrounding low behavior score, once you drop below a certain threshold, the matchmaker puts you onto teams that somehow force you to be below a certain winrate.
Basically, through some kind of fucked up system, you are given extremely toxic low behavior score teammates while your enemes are NOT low behavior score, ruining the matchmaking despite all players having near the same mmr.

I mean just think about it, its not phyiscally possible for someone who better than 97.5% of all dota player to just randomly go braindead and lose all of their dota skills over a few weeks and drop such massive amounts of mmr.

I hate to say it, but there is some kind of massively fucked up algorithm going on here regardeding low behavior score, and this data is proof of that.