I just got finished watching the video from Kang's match, I'm not sure what he was thinking. Mousasi took so long to get that triangle in Dennis had all the time in the world to backdoor out of it. Even if he had to leave his arm in there for an Omaplata attempt. Just flying headfirst into a guy's guard is not a good idea, even worse when his specialty (according the the prefight info) was the ground.
I hope he'll be there mentally in his next fight.