I found a staller, the staller is a player called "IRiseYouFall" and he comes from the clan "Europa Unitum"
Here is proof: https://www.warzone.com/MultiPlayer?GameID=16517951
He stalls any ladder games that his team could be losing, and plays normal speed on all the games that he is winning.
I recommend that everyone blacklists this player to avoid having to play against him, and to warn other players of his behavior.
Edited 11/24/2018 22:25:53