No-one can explain talent, it's an abstract concept.
The only way to measure talent is to clone a person so that physically and mentally you have two individuals who are identical genetically. Even so, you would need to ensure that both are subjected to the same external factors and train in the exact same manner. THEN, you could see if one person can hit the ball better than the other, all other things held constant.
The problem with these talent debates is that people are biased and will go to great lengths to diminish the talent of the player they don't particularly like. Nadal haters will make Nadal out to be a running bull who wins because he has unparalleled mental fortitude, unparalleled physicality and never gives up. Let me explain why this holds no water.
First and foremost, let's begin at the start of Nadal's career. Nadal was born a natural right hander who was made to play left handed by his uncle, they thought this would be a successful formula. Simple question, isn't this within itself evidence of the talent of Nadal? How many people can get away with this?
Let's also consider that Nadal was hyped up as an amazing talent when he was a teenager, everyone talked about him as a very talented player. I remember i saw Rafa back in US open in early 2000s when Rafa was 16 years old and he was being competitive against experienced pros. No-one back then saw Nadal as a muscle brute who was a clay court specialist, everyone saw him as a super talented kid who had a bright future, similar to Gasquet. It was only after 2005 season that people started to speak of Nadal as a clay court specialist.
Let's now consider what he has achieved. Nadal has 16 slams (10 FOs, 1 AO, 3 USO, 2 Wimbledon). He has also made multiple finals at AO, USO, Wimbledon where he lost in finals. NO-ONE and i mean NO-ONE who doesn't possess AMAZING talent can accomplish even half of this.
On aesthetics. Many confuse aesthetics with talent, this is why someone that is fluid is thought of as talented vs someone who is not, not so much. Do fluid strokes and graceful movement have anything to do with talent? There are literally thousands of players who look more graceful and fluid than Nadal in this world and they can't accomplish squat.
Gamewise. Nadal can do it all. Nadal can crush backhands and forehands, just watch how he played Del Po on hards or how he played Wawrinka on clay. In the FO final he wasn't just running down Wawrinka balls, it was Wawrinka who was doing all the running and seeing winners go by, ON CLAY. In this year's USO, Del Po was ready to win the title, he took out Roger and knew that if he could make finals, he could win. He ran into a Nadal that stunned him, Nadal was not just running down balls and making Del Po miss, Nadal had weapons and schooled Del Po.
Rafa has abundant talent, when he is confident, he can beat anyone on any surface. Didn't he beat Federer in 08 Wimbledon? beat Djoker at USO final twice? Nadal has every shot in the book and has even become an accomplished volleyer and good doubles player. I would say that his only semi-weakness is a lack of a huge first serve and i believe this is a product of playing lefty as a natural right hander. If we watch the Giles Muller vs Rafa match in this year's Wimby, the only difference was the serve, Muller basically served his way through the match. Aside from a lack of a huge first serve, Nadal simply can do it all.
Question, if running down balls and hitting with spin is all you need to win 10 FOs, why hasn't anyone else come close? Seems to me that if fitness, mental fortitude are all that counts, there would be hundreds of Nadal's on the tour. It's not that hard to get in shape and be mentally tough, this is overrated.