However, it does not give or take SR itself. To give or take SR, what the system does is compare your performance in the game to ALL the other players who played your heroes in a similar SR rating. That means you're being compared to people all over the world. If your performance is similar to theirs, the loss or gain is average. If you did poorly in comparison, you lose more and earn less. If you did much better than them, then you earn more SR and you lose less if you lost. That's why playing unpopular heroes gives you more SR; because there's less people playing them, and many people throwing or trolling with them, so the average performance is very low and if you do even decently with, say, Hanzo or Torb, you earn more SR than normal.