Hmmm dunno he was much closer in ability to the top three than he was the rest of the pack
He was world no1 at the end of 2016, and probably (although never would have come close to those three with grand slams) would have picked up a lot more of them if not for the hip injury that he never really recovered from
Don’t get me wrong the top three are freaks of nature and he wasn’t quite at that level I agree but not perhaps as far off as you’re stating given the amount of grand slam finals he was consistently making, the ATP titles he won and not to mention back to back gold medals at the Olympics
Special player unfortunate to be around at the time he was