Good reply, Great Hands, and I can also see where you are coming from: what could be called Slam Bias
. It seems to me that your argument for Nadal having the greater career thus far hinges entirely on Slam count which, again, I agree is the most important indicator of greatness, but as I see it you too easily negate the other differences.
The point of my rankings, as I said, is to rank players according to their overall career accomplishments and greatness in as comprehensive manner as possible, which to me includes but goes beyond Slam trophies. And yes, I think part of that is consistency. That's a part of greatness. So when Novak goes out in the SF and Rafa gets upset in the 1R, that has some bearing. Not a huge amount, but it matters - especially when it all adds up (e.g. the difference in their SF totals).
Here's a hypothetical for you. Let's say Rafa continues on his current course, doesn't win another Slam, maybe another clay Masters or two at most and several smaller titles. No more Slams, no more #1s, and retires within a year or two. Let's take a perhaps overly modest approach to Novak, saying that he wins a bunch more titles, finishes #1 this year and wins one more WTF, but only wins two more Slams, and starts declining next year, losing the #1 ranking even. So let's say we finish this way:
Rafa: 14 Slams, 28 Masters, 65 titles, 2 #1s, 0 WTFs
Novak: 13 Slams, 33 Masters, 70 titles, 5 #1s, 6 WTFs
Would you still consider Rafa the greater player, because he has more Slams?
Anyhow, as I said, this is really a moot point because regardless of how we compare the players right now, Novak will almost certainly surpass Rafa.