I've seen Mad Dog's clips a million times, and the guy's a monster. I mean, the whole feat involving the fluorescent light shard being stuck in his neck was done after he'd already taken numerous hits, been kicked into a wall, had his head knocked into concrete and even gotten choked out for a few moments. And even after he got stabbed in the neck, he was still kicking the everloving shit out of the Brothers. They had to basically rip his throat out with it before he finally stayed down for good.
Having said that though, that's...really all he has against Ip-Man outside of being a much more ruthless fighter. As tough as he is, Ip-Man punks guys much tougher and stronger than him. He's blocked blows from a guy who could casually do
this, and stopped blows from Twister (who killed a guy with his fists) by hitting the weak points of the latter's arms mid-swing. Most of his opponents can easily get up from being kicked through railings and furniture, also.
Dog's other problem actually comes from one of his strengths; he takes too many hits. That's going to suck in this fight, since on top of having fought people with better actual durability feats, Ip-Man has him outskilled to the point that it's comical. The guy took down ten Karate blackbelts in a 10v1, and after he got hit in the eye during one of his fights, he managed to do
this. Against a man who, up to that point, was easily keeping up with him and showed far more raw combat skill than Mad Dog ever did.
And that doesn't convince you that Dog is out of his league, then
this will.