Never gonna happen, but if you pay close attention to their fighting style differences:
- Nate uses more his range, is an outside fighter who made his opponent miss while he lands, he has better defensive boxing than Nick, gets hit slightly less but his offensive is not that relentless like his older brother.
- Nick pressures much more than Nate, that mutherfucker get hit more, but never stop to pressure his opponent, and mix his punches, to the head, to the body, much more than Nate too, his opponents end up against the cage, gassed, stunned, with the body fucked up by punches. Its simply glorious.
- Both are cardio machines (maybe Nick a bit more, he is the triathlete)
- with granite chin (maybe Nick a bit more too, no one has KOed him)
- volume punchers (Nate more a headhunter than his brother who aims to body more)
- Nick has been fighting in the upper division and now he looks massive, probably staying in MW
You can say now Nate has the better win against Conor, but Nick fought a roided Anderson Silva and was barely damaged (just look at how fucked up Bisping was to compare, and he is supposed to be the safe boxer).
I can see Nick edging the fight, by being, bigger, more relentless in his offensive, more pressure fighter against the cage, mixing with body punches more, and I think he has the better cardio and better chin (has not been koed recently)
But to be honest probably Nate has the better fighting shape right now, he has been much more active. Sadly, this comparison was an actual Nate Diaz vs a 2013-2014 Nick Diaz probably. But Dominick Cruz said ringrust was a mental thing, so, who knows.