I'm not too sure about the JDS armbar, it looked like a more experienced grappler would've still been able to twist out of it when he tapped. I could be dead wrong about this though.
I watched the whole fight not long ago and felt the same. A lot of people like to say that JDS and Anderson have amazing BJJ games, but I'm doubtful. I think JDS would struggle to get back on his feet, let alone go for a submission, if it went to the ground. I imagine that if they faught in an alternate universe, Nog would sub him if he managed to pull guard.