I'd agree mood is a big factor. It can be a factor in how you will do before you even sit down, if for example you have issues in your life that are on your mind. Or it can effect you hand to hand, for example if you just took a tough beat.
Tommy Angelo wrote about this in his book. I haven't read it but I think he talks about playing your A, B, and C games. It's really tough to try to always play your A game, but it's more feasible to try to AVOID playing your C game, and a lot of that is controlling or being aware of your Mood.