I remember reading in a Black Belt magazine a number of years ago an interesting in hindsight comment by Royce Gracie. He said that because his family had been holding NHB fights for so many years that his family would always have the edge over everyone else. That while everyone was trying to land on the moon, they'd be landing on the sun.
Of course we now know that the complete opposite is true. That the techniques and athleticism evolved so rapidly in MMA that the one-dimensional athletes of just a generation or two ago would be completely overmatched by todays fighters.
So why were these fighters able to hold their dominant position in Vale Tudo in Brazil for so long? Why were fighters representing only BJJ able to be relevant in Brazil for half a century only to be eclipsed in a decade after UFC1? Why would a Rickson Gracie be able to hang with anyone in Brazil in the 80's, but most likely not be a match for an Anderson or a Wanderlei today?