I am not misrepresenting or misunderstanding your post, you are still missing my point which would only benefit you to get a better grasp of it.
It's not that the game doesn't evolve, or that there are more athletic players today than there were 30 years ago or that athleticism isn't advantageous, it's that relative to skill, creativity, ingenuity and ability (not some sort of technique you think can just easily train in your NFL example) it means next to absolutely nothing. It is not some tremendous advantage as you stated.
If you want to talk NFL, you look at the QB nod a DB. Does it matter Tom Brady is slow and old? No. Why doesn't it matter and why has he been able to push the limits of his successful career?
Take two players of equal skill and one's a little more athletic, sure all the better. Take two players of similar athletic qualities and you have even a modicum of difference in soccer intelligence than you going to reap tremendous advantages there and in no other manner.
Back to soccer examples, take the best player in the world. If it's not Messi then it's Ronaldo. One's an elite athlete the other isn't. Doesn't matter, Messi is the best player the world will likely ever see.
Sticking with Argentina, they were a totally disheveled unit kicking their coach off the team basically this last world cup. That affects them way more than anything, way more than having no real fast wingers to get in behind the defense (though you need some yes, but relatively speaking not having that and not having Messi play in more comfortable position for him pales in comparison to other factors like team moral and Argentina not having many playmakers capable of creating for messi etc)
But really the Xavi/Iniesta example was best. Spain plays more directly now than they did then, but it's because they don't have that absolutely insane of a combo dominating the game for them is why they aren't what they were, not because Ascencio isn't as fast as Sterling or they have a tendency to overpossess.