The steam page doesn't mention a single player. Is the so called single player you are talking about offline playable? Or it is bound to a server with just bots instead of humans.
According to the game features Offline practice mode, playing with bots on all game modes.
It's one thing of what developers tells and another thing of what's for real I'm sure we all know this.
What we need to know is that if you plugged out your internet cable, can you play this game and is a trainer needed?
I don't have the game myself, but in making a trainer in offline, high chances are it will be used in MP