This match was tennis in a nutshell.
First set both players playing well, with Grigor raising his game towards the end and deservedly taking it. Second set the momentum swung massively towards Stan (did he take a bathroom break, it seemed so). He was absolutely killing it out there in every aspect of the game: serve, groundstrokes, shot selection.
But then what happened is what happens so often in tennis. If you don't break your opponent while you are on top, you will eventually go off the boil and let him in. Grigor did brilliantly well to hold on to his serve while Stan was obliterating him. And then again he did well by taking his one and only chance in that eighth game of the last set.
Over the course of the match Stan was probably the more on form player and still lost. Which in my book means Grigor did his job perfectly.