I have grappled damn near my entire life, i feel like you are getting carried away by nostalgia. They would probably get submitted with a move they have never seen before, leglocked, knocked out with a kick that they never learned how to defend, just plain gassed or very possibly knocked out with ground and pound. DJ may really be on another different level. No one in UFC 1 knew what they were doing or what to expect, MMA training didn't even exist, people trained boxing and BJJ or wrestling totally separately, i doubt they even knew how to check kicks.
I absolutely love Royce and the old guard but this is what i believe in, i do think the sport has evolved this much