You're arguing a moot point because Nadal is the least talented out of the top 4.
That's pushing it IMO.
Based on pure tennis shotmaking ability and feel for the game, Fed is clearly the best. Djoko and Nadal could be tied. And Murray is easily the last. There's a bunch of things just plain wrong in Murray's game, not least his DTL forehand technique and his putrid second serve.
Nadal is outclassed against Djokovic not because he's a inferior player but because he doesn't have the tools at this time to surmount the matchup problem. If Nadal were a "significantly" inferior player to Djokovic, there is no way he would be beating the rest of the field so easily. It can be argued that in the Wimb, UsOpen 2011 - Nadal had an easier time against everyone else than Djokovic did. In other words, against Djokovic, Nadal underperforms "significantly" to what his ranking might suggest.
The problem that Nadal has against Djokovic is similar to what he has against guys like Davydenko and Nalbandian. Except Djoko doesn't miss like those guys, and he's now fitter and stronger than even Nadal.
Those who can't see the matchup problems probably never played tennis. In both the standard cross court rally patterns i.e
- Nadal's forehand to Djoko's backhand
- Nadal's backhand to Djoko's forehand
Rafa gets burned. His offensive play in pattern 1 is totally neutralized and pattern 2 is when Rafa gets behind and goes on defensive on his weaker wing. Djoko has the ability to expose Nadal's backhand much like Davy/Nalby etc do (when they play well). That's why the story of their matches is Nadal being pushed back and Djoko standing on the baseline. Unlike Davy/Nalby/others, Djoko can pound Nadal's backhand repeatedly without missing.
Trust me, when you are on a court against a player who neutralizes your strengths and doesn't allow you to go on offensive, it's almost impossible to play well or to remain mentally strong. Every time you try to get ahead in a rally, you get pushed back. It's incredibly debilitating. The only REAL option Nadal has against Djoko is to change direction inside out or DTL which are always low percentage shots for him.
In the 3rd set of the UsOpen final and after the 0-40 down in the 4th set of AO 2012 final - Nadal played some remarkable tennis, which is far above his usual level. He played with intensity, depth and aggression like a man possessed. Despite getting outclassed from the back of court, he somehow just willed himself to hit harder, flatter and push Djoko back. I haven't seen any other player fight like this when he's getting dominated throughout the match.
That said, it's almost impossible to for Nadal to play like this for the whole match. It's easier to do this when you're behind and have nothing to lose. Which is why it's hard for him to beat Djoko until the Serb plays at his current level..