In a recent interview, Rickson Gracie spoke at length about the different ways in which a jiu-jitsu move can surprise even him. Check out the third part of his thoughts below. And in case you need to get caught up, find part 2 here.
"Another is when you lack posture or have no weight distribution, or you have a poor placement of your arms or shoulders, and then the guy gets you because you make the mistake. And then the approach will be: make the guy not make those mistakes anymore.
"So I quickly realize if it was the personal ability or if it was a student's mistake; and from that, I start to add—either I'm gonna add to my repertoire what he just did, or I'm gonna say, 'No, man; just don't lose your posture; the guy cannot give you— He never will sweep you here if you just keep your weight this way. Here's never gonna choke you here if you keep your neck this—'
"So, if it's based on the student's mistake, I correct the mistake. If it's based on the ability of the attacker, let's train the ability to develop that kind of sharp element of finishing."