This is definitely a tough one.
On the one hand it’s difficult to ignore one fighter getting dominated and nearly finished at the end of the last round.
On the other hand the number and duration of rounds are parts of the rule set. While it’s tempting to suggest that fighter A might benefit from a different set of constraints on the contest, there’s no way of knowing how fighter B might prepare differently for what is essentially a different contest.
Would Nate have benefitted from extra rounds? Yeah, he definitely would have. But chances are Leon would have fought differently under a different rule set. And there’s really no way of knowing if those exact circumstances would have presented themselves.
At the end of the day, while I have nothing but respect for both Nate and his brother, this bout is indicative of what we already knew; the Diaz brothers Achilles heel is their inability to tailor their fighting styles to the rule set under which they’re competing.
I have no doubt that Nate could procure a street fighter were he so inclined. But I suspect the compensation for such a bout may be less than enticing.