The notion that Schaub's chin suddenly "gave out" is misguided considering he had been KO'd various times throughout his career (even by Nog who was never a power puncher) and not just a bunch of times at the end. Chuck's chin was once great but "gave out".... Schaub never had a good chin.
That being said, this isn't a ridiculous fight and Schaub was a decent fighter in his day. To answer your question, I'd still have to say Brock via TKO. Schaub was fast but I doubt he's faster than Brock and I've never seen Schaub face a decent enough wrestler to give me the confidence that he could stop the takedown. If Brock got on top of him once, which I think he would, one or 2 of those giant hammerfists would easily put out Schaub's lights.
Brock via TKO