I gained 90 MMR in my last game

Hey there,

I got a question about MMR gain.

So, I'm usually pos 4 player and was at about 3.7k MMR.
Then I decided to invest more time into dota, get coaching and see how high I can climb.

Since I play alot of normal/turbo and mostly play carry there, I decided to get a coach for pos 1 (played 1-2 pos 2 games).

With the coach, the games felt super easy, I learned a lot and carried very easily. By the time the coaching was over, I was at 4040 MMR.

After the coaching however, I felt like pos 4
Is way more fun to me, so I started queueing 1+4.

I lost couple games, won couple, but lost more than I won (6-8 maybe). So I was at 4k MMR exactly

Then yesterday evening I won a game as aba (4) and double downed. (Had almost 50k healing and good stats)
After the game, I got instantly promoted to ancient 3 ( was ancient 2, 11%).

Ao I checked my MMR, and it says 4180 now.
So I got 90mmr from 1 game.

Is there any ideas how that might have happened?

I googled/reddited abit about this topic, and only found things like "Smurf detection", but because of a few (maybe 10) coached games, I doubt that's what happened

Is there any theories or does anyone even know the reason, why that happens?

I mean I'm happy, but can't get my head around it

Thanks ahead and gl hf all <3