According to Steam, the peak CS:GO player numbers have reduced dramatically since March, dropping from a peak of 640,000 the Saturday before the major to 480,000. This data is based on SteamDB’s numbers for players, which is gathered via Steam’s API, and ESL’s VP of Pro Gaming giving a viewership number on Twitter. In-game reporting tells the same data, via Reddit. Who steals the fans of CS:GO? Let's see.
1) The Success of Overwatch
As you know, Overwatch from Blizzard is a great hit which definitely affected both viewership and player numbers as general interest in the game is taken away.
2) Cheating Scandal
There’s recently been cheating issues in the game, followed by the introduction of a prime matchmaking group which means hackers usually end up playing against each other. Besides, the recent drop in the skins economy and related scandals, could have caused some disinterested. What is worst, unable to gift the game which impact on third party sales greatly.
3) The Tournament
The tournament itself had some impact too. The most popular European teams went out early, while the South American and North American audience would have had a very early Sunday morning to catch the finals between their two representatives. What is more, the finals were broadcast on harder-to-measure TV in the home country of SK, Brazil.