Look, dudes, the four best players in the world are all literally identical heights, with Murray being maybe a 1/2 tall than the rest. It's laughable, this mumbo jumbo about Nadal being 6'0". I've stood next to Nadal, a foot away, multiple times at IW and he's just as tall as I am and I'm 6' 1" 1/2 on the dot. It's quite weird to actually see Federer, Nadal, and Djokovic in person, close up. They don't come off as particularly tall on the television screen, but seeing them close up, I'm like, Damn, they're kind of tall just like me (not that I'm a giant or anything, but given that the average American male is 5' 9", we're all definitely on the tall side. I'd say Murray is 6' 2"--6' 2"1/4.
The discussion of heights can end right there. At the elite level of the game, there's something about being about that height that maximizes ball-striking effectiveness. In a game of millimeters, striking a short ball (inside the baseline) with you forehand four inches higher than a player that is 5' 8"-5' 9" is going to add up to a huge difference. And serving, well, that just self-explanatory why height would help.