Great dogfight from Andy. A real improvement from recent slam performances against the Big Three. Still, at that level you can't afford the fourth set he had: so momentum-robbing. Worse, the shift between the end of the third set and the beginning of the fourth was a snapshot of the entire match, where Andy had difficulty capitalizing on Nole's subpar play...and more difficulty maintaining momentum once he did.
The reasons for this seem multiple. Sure, his mental strength is not equal to the Top Three's. But he'd be stronger mentally with a serve that gives him more free points, or at least consistently places him in control of the point. It'd be easier for him to build confidence if he simply stopped playing rope-a-dope (which always let Nole get back up) and stayed with the controlled and crafty aggression that was continually drawing errors. Lastly, he was notably worse at fighting through physical issues than Nole, who made the third set so tough that he was able to get a second-wind just from seeing Andy fatigued in the fourth. He did something similar to Rafa at the US Open, so the Scot and Spaniard should be aware of what awaits them at each contest from now on.