One reason Nick is able to pressure lesser opponents is by taking the ball very early in both attack and defense. It is the position and speed of his initial racket preparation allows him to do this. Look how his racket is ready really early but not too high at first.
This shorter swing enables him to attack very quickly with a volley or half volley, short or long, straight or cross-court. If he decides he would be better served by going to the back of the court for the ball he then has the time to get racket back farther. He generally uses a full swing for hitting the ball after the back wall.
This short early racket preparation also enables Nick to defend immediately if required, usually with a lift or drop. He prefers to try and defend the ball quickly before he gets into more trouble and before his opponent has recovered enough to take full adavntage. This places pressure on his opponents to try to do more with the ball and then they begin make the errors!
So the coaching point here is that there is no one-size swing. It is dependent on the time you have and the decision you make. An initial shorter preparation will allow you to be ready to take the ball early, from where you can draw the racket back more if necessary.