You dont understand where is the problem...
9 and 11 games is a very small sample. If you win 9 in a row it's going to push your MMR up significantly, which often leads to a hard correction as you're suddenly playing in matches were everyone is better than you, but that won't correct for at least a comparable number of losses (maybe more if you've had a history of outperforming the rank below you).
That was basically my lot in life previously playing Overwatch. I'd hover around the silver/gold line (not very good, I know, I freelance way too much and only play solo, so constantly get trapped in 2v1 and screw my team). I'd win a bunch, be on that line where suddenly my games are at least as many gold tiers as silver tiers, get smacked back down, and as soon as I was playing all silvers again I'd take player of the game repeatedly and start climbing back up, only to repeat.
There is nothing actually wrong with Overwatch's match making, we're all just guilty of cognitive dissonance and remember our wins more fondly than our losses. Marshall Goldsmith asked a MLB batter in his book "What Got You Here Won't Get You There" what he was thinking when about to face a pitcher he's hit well and the response was "I own this guy, I hit him every time I see him". When asked about pitchers he historically fared poorly against? "I've hit better pitchers than this chump". This for a profession where great success is failing 7 out of 10 times.
