It doesn't make the question any less valid, does it? If you want to evaluate the overall level of opposition in each slam, you have to consider all the opponents; not just the ones who fit within the top 5. Your argument is: "well that's too much work". OK, but that's just means we don't reach any conclusions.
All you're going to do is make UNSUBSTANTIATED claims about Djokovic's opponents to detract from his victories, so why even go there? Here: I'll even set it up for you. Let's take a look at Federer, Djokovic's, and Nadal's very first slam and consider ALL the opponents:
: Becker, Bolelli, Querrey, (19)Hewitt, (5)Ferrer, (1)Federer
, and Tsonga
: Burgsmüller, Malisse, (30)Gasquet, (23)Grosjean, (20)Ferrer, (1)Federer
, and Puerta.
: Lee, Koubek, Fish, Lopez, (8)Schalken, (5)Roddick
, and Philippoussis.
Anything jump out at you? How many cripples did Djokovic had to face and how many legends did Federer had to power through? Because as we all know, seed is irrelevant, right?
It doesn't mean you can decide arbitrarily, just because you're too lazy to do the actual work (i.e that outside the top 5 there was no difference in the average rank of opponent). In any case you haven't even made any arguments, based on the data you supplied. Data without interpretation is meaningless.
Maybe the concept has escaped you but it's quite possible to set up boundaries for an argument and not jeopardize the conclusion because of what has been omitted. I know you want to include as much superfluous information as possible in an attempt to bury the main argument but I'd rather not indulge in that nonsense.
And here's an argument: Djokovic's faced tougher opponents.
So Nadal faced 0.11 more top 5 players per slam than Federer. Great! Do we know how often each player towelled off during the change of ends? Maybe I should present that data in a new thread.
Maybe you should and we'll see how many people care