Oh, he has the ability. But, whether he has the guts to pull the trigger on important points is the question here. He has won so much by pressuring his opponents to collapse and give him errors. It's actually a tough dilemma for him. "Do I pull the trigger and end the point here? It would be better but it only has a 60-70% success rate. Or should I rely on my legendary defense, that has been proven to work 90% of the time, and wait for him to give me a sitter or make the error?".
Me, personally, would go with the 90%. Say what you will about Nadal's game, one thing's for sure though, it works. Like a charm.
Well, it didn't work against Djokovic in all of those lost slam finals and MS finals, did it? That's what I'm saying, it's those situations where a real offensive weapon like that could be a match changer. Yes, Nadal does possess a weapon in his forehand, but he's not winning points as efficiently as he could be if he developed the shot we're talking about. Hitting 4 pin point forehands out wide on the AD court with enough angle to Djokovic's backhand before only possibly
leaving a short ball to the forehand side to make the shot down the line a point winner is far more gruelling physically and mentally as well as dependant than having the ability to crack one to either end the point or leave a mid court forehand, which Nadal specialises in. It's also something that cannot really be anticipated (and leaves your opponent with less of a rhythm) and if, somehow it is, is extremely difficult to work with.