How old are you? Genuinely curious.
Football/soccer was a little slower on adapting to the modern standards of professionalism seen in the North American team sports, however, your first statement is simply not true. When people say this, I have to assume they are often young, perhaps even less than 20 years old.
I can assure you, that almost nothing has actually changed in terms of sport specific training in the last 25 years in virtually all major professional sports. Nutrition hasn't really changed much either. The main difference, is the diffusion of knowledge. Good training advice is readily available for anyone who wants to find it. 25 years ago, this advice while there, was less available. Your coach or trainer had to have a pedigree or some sort of connection to someone who knew what was up. Now anyone can go on youtube, and find good techniques, good programs, good systems.
If you're telling me that David Beckham would be run off the pitch by anyone on any team in the premier league today, I'd tell you I have a bridge in Brooklyn to sell you. The simple fact is, the "great revolution" in modern sports, came in the late 1980's and early 1990's. Since then, not a whole heck of a lot has changed. Tactics have changed, how people strength and condition hasn't.