If I am fighting a guy, and he claims to be able to beat me anytime anywhere, yet i get in the ring and draw out a stale mate....well then he couldnt beat me any time anywhere.
If you severely outclass your opponent to the point you can beat him any time anywhere, he wouldnt be able to draw out a fight for 30+ minutes. Now on the other hand if you were relying on a skillset, and your opponent found a weakness in your game and exploited it, then that is exactly what happened.
Your weakness was exploited, regardless of what that weakness may be.
Shamrok exploited a weakness of Gracies personal game.
Happens all the time, especially if you have any amount of time to study your opponents fighting habbits.