As for the argument that equipment, training, etc are responsible: that would be true if we were talking about quantitative records, like longest drives, lowest scoring averages, fastest serves, etc. Advances in equipment, training and technology do NOT explain why ONE team or ONE player in a given era is capable of dominating a sport. The Pats aren't using a ball that is different than any other team uses. The players that Federer annihilates have the same nutrition and training and equipment Roger has. All golfers have the same clubs, balls, courses, teachers that Tiger has access to...
In fact, the lucrative nature of sports recently has made it HARDER, not EASIER to dominate a sport today relative to, say, forty years ago. Nicklaus played against a weaker field than Woods I'm sure. How many Japanese or other Asian pros were competitive in the 1960s? Now, the whole world can play. With tens of millions of dollars in purses, not a few grand, at stake, the fields in tennis and golf have gotten deeper. Likewise, the talent pool in the NFL has grown deeper and more distributed. What the Pats have done in this era, not just this year but over the last five, is amazing.