How does Overwatch determine your ranking? Is it simply over your wins and losses or does it take into account how you actually perform?

For context, I am a tank main and typically outperform the other tank on every metric. Our team will have our damage players at about half of what the other teams damage players have caused. Obviously I have had some bad games, and I know I still have a ton to learn. but i got a low ranking after my first 7 wins and I was expecting a higher one based on how I performed. The only thing I could think of was the results heavily outweigh one’s performance.

I just want to add that I played overwatch 1 a handful of times and started playing overwatch 2 last week and I forgot how fun annoying the game can be at the same time. Looking forward to grinding some more!