Has Parity Really Worked In The NFL?

[FRPLG]

Do we really know whether teams are worse than they used to be or are other factors invovled? For instance I often wonder if rules changes have made it so difficult on on defenses that they simply look bad because it is so stacked against them. I think it is extremely hard to compare quality of play from one season to another because of all the variables. My guess is that if there was a quantitative way to compare quality of play from one season to the next that we'd realize that fundamentals are less developed but athleticism is far superior than even 10 years ago. I'd also guess that the increase in athleticism more than makes up for the fundamentals lapse. Of course everything is relative so all that athleticism should balance out accros the league and then it all comes back to fundametals. Which is maybe why it seems that the play is so mediocre now. I don't know. My head hurts now.