I watched a rerun of the UFC Unleashed episode which focused on Royce, and one thing I noticed was most of the fighters he faced failed to do some very rudimentary things to counter his submissions. Things which a fighter today with any round game at all would be trained to do.
Keith Hackney was outmuscling him and for a while showed what today would be called takedown defence, but got too frustrated trying to get punches through and got caught. Jason Delucia could easily have rolled out of that armbar before Royce cinched it in if he had any idea what he was doing.
It was the first time I watched the Kimo fight, and I found myself practically yelling at my TV, because there were times where the bigger strnger Kimo could have slapped a submission on Gracie himself. He also could have thrown him or gone for a choke when he had his back standing up, but hesitated too long and Royce dropped down and went into guard.
I think part of it was by that time guys like Kimo knew what Royce was about, but hadn't figured out how to counter him. Instead of taking the fight to him, they panicked and focused on not going to the ground. What you had was a stalemate which finally ended when Royce fond an opening.
I'm not trying to take anything away from what Royce accomplished in those fights. He was way ahead of his time as far as MMA was concerned. But if he was entering the game today, he'd have to train for today's game. A Royce Gracie trained in staright 1993 BJJ wouldn't do nearly as well.