Djokovic may not have been at his best but a lot of that had to do with Federer's amazing play Roger is still clearly the better of those two on grass!
Nerves aren't much of an excuse for Murray seeing as he won the 1st set and was competitive in set 2! The problem for him was Roger raised his level to a level that Murray could not handle it was unfortunate for him.
No the problem was the roof came into play and Murray failed to adjust.
he was also still tentative in the 2nd set when he could have went up a double break.
The roof sealed the deal.
It wasn't just nerves but also being less experienced and also unlike federer Murray had an extremely challenging draw so mental fatigue will probably have been the final nail.
None of these issues, despite the ITF's best attempts should come into play again,at least not as much weather permitting.
Although Andy had a better handle on his nerves, which given the occasion was admirable, he was still definitely nervous.
Anyway whoever wins in the final wins, fair and square.