SR is based on the Elo system. The benefit of Elo is the system is self-adjusting. If you win alot, then you move up in rank. If you lose alot, then you move down in rank.

However, there could be some inaccurate period where a person’s SR is getting adjusted. Suppose a GM Tacer one trick loses his left hand but still wants to play. He plays Overwatch with one hand. He will lose games, but it will take awhile for him to lose enough games to drop in rank.

Conversely, suppose this GM drops to Bronze but then receives a bionic hand. The current Bronze player starts winning games, but it will take awhile before he wins enough games to get back to GM.

So basically, SR is accurate in the long term, but could be inaccurate in the short term. People usually get tilted when they think their skill is higher than their SR. But if you aren’t stomping the enemy team, or is not getting stomped by the enemy team, then you are at the right place from Elo’s point of view.

For first time Placements, an algorithm examines your performance and makes a guess at your SR. The algorithm could guess wrong, but later games will adjust you up or down depending on your winrate. Basically, don’t worry about your SR accuracy after Placements, it’s going to be an estimate. Your SR will be more accurate after 20-30 games.