Royce wasn't even the best Gracie brother at the time. Those early days of UFC, nobody knew what the heck BJJ even was, let alone know how to defend it. A guy like Mir would have killed Royce Gracie. Years after those early days, Royce fought champion Matt Hughes who technically didn't even have a jiu-jitsu belt (although he stopped many guys using high level jiu-jitsu). Hughes was just a country strong wrestler who was far better at jiu-jitsu than his lack of belt would suggest. Hughes easily defeated him. At one point of the fight, he popped Royce's elbow out with an arm lock and Royce didn't tap. He just repositioned and put it back in on the fly. Shortly after that, Hughes took his neck and ended it.