Everything in baseball is mental. Pitching is mental, hitting is, fielding is.
But when you try to hard (pressing) usually when your in a slump, but also when you feel like you have to prove something, it can affect your mechanics. Also, when your tense, you won't get as much as you could from your swing, from your throw, as you could if you were more relaxed.
So, is why your crushing the ball because your so relaxed and confident at the plate? Well.. it can't hurt, thats for sure! I'd say it's deffinately a big big part of it. So keep up the good WORK!