What I think Andy has done, which to my mind helps him with any opponent, is win the battle with himself. Take that semi at Wimbledon in 2011 for example. Was it me or was Andy playing that first set with a 'Do not make a mistake, do not miss', attitude? Well, for a while it worked. Andy was a set and a break up when he missed a forehand. Andy got down on himself. He made another error. He got more down on himself. From then on Nadal must have thought all his birthdays and Christmases had come at once. Andy began to lose his grip on the match and Nadal took control. Nadal won in four, and I have to say I was gutted. I honestly felt Andy had lost the match between the ears as much as with his game, perhaps more so.
I think the exact opposite. Andy was playing the 1st set highly aggressive and it was some of the best tennis he has ever played, Nadal was playing really well in that 1st set as well. Then in the 2nd Nadal started playing out of this world as he often does against Andy, and Andy wound up making a few UEs with his aggressive play because Nadal was getting everything back but over-all Andy was playing very well in that 2nd set still. In the 3rd and 4th sets Andy continued to play very aggressive (in fact over-all I think it is the most out and out aggressive match I think I have ever seen Andy play) but his level dropped a bit and he started making UEs as you should somewhat expect considering how aggressive her was being, Nadal also possibly started playing even better; I felt overall Andy had no chance in that match with Nadal playing at the level he was - no way did I see Andy sustaining the level he showed in that 1st set and even if he did Nadal probably stepped his own game up to that level as well. Andy said in interviews afterwards that he was too aggressive in that match it was the wrong approach to it, he should have stopped pressing so much after the 2nd set.
The stats alone show how good Nadal was on that day, I don't think people quite realize how well he played:
Murray Nadal 7
15 Aces 6
135mph Fastest serve 128mph
58.00% 1st serves 68.00%
73.00% 1st serve win% 81.00%
49.00% 2nd serve win% 58.00%
5 Double faults 1
37 Winners 42
39 Unforced errors 7
1/4 Break pts 5/8
UEs in a 4 set match against Andy, 7! I challenge you to find a better UE stats than that for any match played against Andy, Nadal or Djokovic in the past 5 years. I think I recall Nadal made about 3 or 4 UEs in the 1st set, then 0
UE's in the 2nd set (I wonder why Andy lost that one?) and 1 or 2 apiece in the 3rd and 4th sets. To put it in perspective Andy made 21 UEs against Djokovic in that 3 set win. I think Andy's UE count was like 2 in the 1st set, then 5 or 6 in the 2nd set and then he started making quite a lot in the 3rd and 4th.
However looking at things now the game has moved on, I've seen Djokovic putting in sublime performances week in week out to the level that Nadal was displaying in that match - at time it seemed more impressive because quality like that wasn't as common place like it is now. In consideration for the match-up at present, I think they will be on more of a level playing field because Nadal's game has dipped a little from it's best and Andy's has improved that extra 10 or 15% he was looking for since 2011, it will certainly be interesting to watch when they are paired up again.