I think Mir running his mouth is just him trying to make sure he doesn't have to fight Nog again because he knew something was up. He's trying to dismiss the "excuses" so he can say, "Hey, we fought and I won. No reason to fight again."
Compare Nog in the Herring fight to the Nog in the Mir fight and it's obvious something was weird. 7 days in the hospital with a staph infection (I assume) aint no joke. Shit, 7 days in the hospital for ANYTHING aint no joke.
The thing about a lot of these fighters is that (at this level) there's so much at stake with each fight, especially when you take the outcomes of other fights that aren't theirs into consideration, they don't want to chance any kind of setback.
Think about the LHW title picture back when Forrest had the title. Who gets the shot if Rashad doesn't Super Macho Man Chuck's face off? Rashad got the title shot strictly on that performance.