"Back in Season 2, we introduced a skill rating decay system, which required players in the Diamond, Master, and Grandmaster tiers to complete at least one competitive match every seven days in order to maintain their status. This season, players with a skill rating above 3000 will need to complete at least seven games per week—a change that will improve the accuracy of the player's skill rating, make maintaining multiple high-level accounts more difficult, and make upper-tier placement more meaningful.
Some players, for instance, have been deliberately throwing matches in an effort to reach the lowest attainable skill rating. We obviously don't want to incentivise this behavior—because Competitive Play works best when everybody is trying—so we're making it a little more difficult to hit the lowest and highest possible ratings: 0 and 5000. We're also no longer displaying skill rating values that are lower than 500. This change will have no effect for players who have a skill rating between 500 and 4500."
Det är även ändra förändringar på gång, surfa över till denna länk för en komplett genomgång.