“I’ve seen comments like “I just won three games in a row, so the matchmaker put me in a bad stomp to get back to a 50% win rate”. It doesn’t do anything like that at all. It just keeps on trying to find fair matches. If you do win more than you lose, your SR will slowly go up. As that happens it’ll also put you up stronger opponents that match your new SR. That’s not so you lose, it’s to keep your matches fair.” – Scott Mercer Overwatch Forums
“At no point in MMR calculations do we look at your win/loss ratio and win/loss ratio is never used to determine who to match you with or against. We are not trying to drive your win/loss percentage toward a certain number” – Jeff Kaplan Overwatch Forums
Analysis of Streaks in Overwatch, confirming that no funny business is going on: Overwatch Forums
SR and MMR are only confirmed to disagree during decay and DCs. Even though MMR is hard to get a hold on (because it is invisible) we can see SR getting pushed towards a particular value, not by selecting opponents and allies to rig matches, but by changing how much SR is won/lost after a match: 3000+ Skill Rating Data and Analysis (now including DCs)
General discussion of Overwatch’s ranking system: How Competitive Skill Rating Works (Season 13)
The philosophy behind most modern ranking systems (discussing Microsoft Trueskill, which is similar to Overwatch’s ranking sytem): Computing Your Skill
That should keep you busy for a while 