Well, here is my philosophy. It it rains more in my county, I can conclude that there is more rainfall where I live, or just that if I look at a wide enough area, over enough years, it's pretty even. Sort of like how many hurricanes we get.
I figure the amount of talent in any give 5 year period is probably about the same, but anomalies make it appear uneven. Like in 2000-2003 the top 100 players were probably not weaker, but the distribution was more even and with fewer standout players right at the top.
You hear Groundhog Day here daily. Fed was a weak era champion, and right now is the worst tennis in the history of the world, and that's the only reason the top guys are winning. I would say that in the next 10 years or so, if it is obvious that the level of guys in the top 20 is lower, all of them, then something has happened to drive down the level. But I want to see that first. Otherwise I conclude that a bunch of nasty, small-minded people are just being stupid.
That means that as long as Novak goes on winning, even though he is not my favorite player to watch, I'm just going to give me full credit. Like in the AO this year, to me it seems pretty obvious now that he had that muscle tear, and the way he came back is impressive. You will never hear me say a word about weak eras or GOATS. I think that's all nonsense.
But the one thing I will say, from being much older than most people here: If you compare tennis at the beginning of the open era, it was a different sport. You had guys winning without personal trainers and private coaches (Laver and Rosewall), playing on soft, uneven grass, using rackets that were heavy clubs, canvas "tennis shoes", no MRIs and advanced surgery, just gut. Those guys were TOUGH. If you look at the tennis, it's like trying to judge a pianist playing on a harpsichord and then saying the harpsichord player doesn't sound like a modern pianist. Or hearing someone play natural horn (no valves) and then concluding that people playing on modern horns (two sets of valves) are "better players" because they don't miss notes.
If you know it was a different sport, then you compare those guys against the guys they competed with, in that sport. Then you realize that even if the 90s look a lot more like today, it's just a matter of degree. So that's why I never compare Laver with Pete with the Big 3. It's a totally unfair comparison unless you actually played with that old stuff (I did.)