Respectfully, I disagree. Neither Diaz brother is a proven draw or big seller. They've had some good events (Diaz/Conor/Conor, Diaz/GSP/Silva), but the majority of that credit goes to their opponent. A Diaz/Ferguson fight is a die-hard fans dream, and would be fireworks for as long as it lasted, but I don't think that necessarily translates into big PPV numbers.
That being said, a PPV against Diaz would never bring Ferguson the sales, exposure, or money that the Conor fight does. I think Diaz has enough skills to make it dirty and bring a battle of attrition to Tony and not worth the risk. I would have Ferguson as the favourite to win, but not by a wide enough margin to think it's worth risking the future title shot against Conor if he's patient.
But both of them would most definitely have some choice words for Conor.
I think they both are proven draws & big sellers as long as they headline UFC PPV's with atleast some form of proper promotion ahead of the fight.
Of course there are diffrent levels in the game of a " proven ppv draw".
Conor, Rhonda & Brock are superstars, you could match em against anyone and it is a massive probability of it breaking 1 million ppv's and so on.
Neither Diaz bro is at that level, same can be said about about fighters like Jon Jones who has several not so good ppv-records, but after the 2 Conor fights the Diaz brand has increased tremendously, they've had big media exposure outside of the realm of UFC during the 2 last years. Always appearing at hot spots in Vegas/LA and so on signing stuff for fans.
Even if a Diaz bro against some other less popular and famous fighter (like Woodley/Ferg) will not break 1 million PPV it will still do 100% better than some of the other relevant fighters in those divisions.
Kevin Lee can promote like hell, someday he can be very famous, he is still very young but he vs Ferg did just horrible numbers, neither one of them has a large amount of loyal fans behind them, same thing for Woodley, as a co-main against Maia he probably contributed zero to the PPV, and hurt his own brand and the UFC brand by participating in a horrible fight.
Woodley vs Nate could do about 650k without problems, while Woodley vs another elite WW (not GSP) maybe does 250-300k, thats more than a 100% increase with a Diaz bro as the opponent.
Do you see the difference in numbers?
So despite not being some guarantee draw (Conor, Rhonda, Brock) the Diaz bros still "move the needle", I promise you that.
And best case scenario Nate becomes the champ and they could sell even more PPV's by matching 2 champs against each others.
Who knows maybe the UFC finance stuff for Nate in this fight in order to increase his chances, Conor got a complete UFC gym financed by the UFC ahead of one his fights, why can't the UFC finance a really proper camp for Nate(bring in world class wrestling coaches and sparring partners in order for Nate to stop a couple of take downs?) if they can gain much if Nate becomes the winner, why NOT?
I mean Woodley as the WW champ has become a massive burden for the UFC, he is boring as hell, they want to get rid of him fast as possible from the WW throne!
The contrast between Woodley and the 3 earlier ww champs can't be larger, no matter how you view it, there is nothing positive for the ufc with Woodley as the champ.
If Nate wins they'll do, Conor vs Nate Diaz 3 for the WW belt of course, since Conor still be the A-side, and has his LW belt left in case of a loss. And then GSp faces the winner of that fight for the WW-belt.
In other words atleast 2 ppv events that easily breaks 1,6 million PPV's.