Both Nogs are going to lose.
Big Nog has looked awful in his last fights. Against Big Country he was too slow and had no answer to Roy's right hand. I'm sure he knew that's what Roy comes to fight with but he still got clobbered again and again. Finally he got hit on the button when Roy started charging his right and stepping towards Big Nog. Nog took a step back, threw a lazy jab and that's when Roy timed his swing. Also notice how low Nog leaves his hand after throwing that pawing jab.
To Big Nog's defense he had been hurt a couple of times in the fight already so maybe he was out of it. Anyway I'm sure you see where I'm going with this. You can't be as slow and stiff as Nog is these days and expect to get away with it. Big Country has great power and he times his bombs well, but let's just acknowledge that he wouldn't have hit prime Nog like that over and over again. If memory serves me right Big Nog looked bad against Herman as well in his last victory. Of course Herman looked even worse, doing nothing in the stand up even if he was faster and stronger.
I see Struve hitting Nog a couple of times with good shots, probably in the first few exchanges. Later as Nog stumbles around after getting clipped Struve won't be holding back and finishes him with a couple of right hands.
Little Nog has looked as stiff as his brother and I can't see it ending well for him either. Against Rumble he was out of his depth (in retrospect). He was stiff and slow, kind of hesitant but that might be because of Rumble's pressure and scary power. He has only fought twice in the last 4 years and has been injured a lot. I remember someone saying that Brendan Schaub had seen Little Nog backstage warming up and was shocked how stiff Nog looked. Like he couldn't hold his hands up (without forcing it?) and his punches looked off. That kind of stiffness doesn't just go away at that age I'm afraid.
Shogun has deteriorated as well but he still has power. That's the last thing to go and I could see Nog being a little slow here and there, that's exactly when Shogun will capitalize and hit him with a big hook.
Shogun and Struve are the rightful favourites in my opinion.