Right. It comes down to the decision to take Long over Ryan. In hindsight, Ryan was a franchise QB and arguably worth the #1 pick overall, but at the time 2 teams had enough questions to pass over him.
Like most endeavors, it takes a team. For Parcells, the original team of people that he worked with and with whom he was developed with under Ray Perkins have been cast to the four winds across the NFL. As more and more teams have bought into the same philosophies, the advantages become commodities in everyone's toolbox. While it's fun to take shots (especially since Buffalo is the only AFC East team he didn't work for making him a sort of archvillian) and we can level some well-supported criticisms against Parcells, he has had a tremendous influence on the modern NFL in many different areas.