Chelsea are one of the teams in the EPL who are very serious but the manager doesn't have the balls to admit it and I believe he has made the player to accept it that they're not in any way qualified to be title contenders. Is a shameful thing to say that a club you're managing are not yet in the title race even when you see how awesome you team have been doing even better than the current Champions and the league leaders. I think Enzo Maresca learnt a lesson from the other coaches who got fired, he noticed that the Chelsea club and the fans have this kind of pressure they inflict on every new manager to always take them to the top even when they know is not immediately it had to happen. Enzo is not really using mind game per say but he is avoiding being pressured and he also wants the players to play without pressure and he feels it will help them do well.
I understand why you are sad with Chelsea manager Enzo Maresca for saying they are not likely to win title. But I think he is smart and trying to take pressure off players. By not making big promises Maresca is creating more relaxed atmosphere where team can focus on playing well without feeling too much stress. This might actually help them do better in long run as they will be able to play more freely and focus on one game at a time. Also Maresca might have learned from what happened to previous Chelsea managers who faced a lot of pressure and criticism.