(It’s a Nor-Cal thing. Or something. VidProps: MMA Fighting)

In successfully defending his welterweight title on Saturday night, Nick Diaz underscored exactly why he is Strikeforce’s most compelling and valuable property. Diaz possesses the total promotional package — the stand-up, the grappling, the trash talk, the antisocial personality disorder – and at this point it’s clear that Scott Coker needs his blend of credibility, charisma and troubled-foster-kid charm more than almost anyone else on the SF roster. We give him a lot of shit on this website (almost all of which he richly deserves) but after his command performance against Evangelista “Cyborg” Santos in this weekend’s main event, it was impossible not to come away with a greater appreciation for the wonderful train wreck that is Diaz.

From his recent conference call outburst to his shellacking of a game Cyborg to the fact that when the fight was over Diaz couldn’t wait to walk to the side of the cage, flip off some random hecklers in the crowd and call them “fucking bitches,” it was a pleasure to watch him work. There’s just something about this guy: We can’t take our eyes off him and yet as the video at top proves, it would be totally insufferable to actually be around him for longer than five minutes. In that way he’s kind of like a bizarre, badass Milla Jovovich.

Diaz struggled a bit early with the torrent of inside leg kicks from Santos – all of which he accepted without so much as a crack in his mean mug – but by the close of the first round you got the feeling we’d seen everything the challenger had to offer. Though Cyborg came out for the second just as eager as in the first (even again arguably controlling the opening few minutes), it was plain to see that the momentum was slipping away from him. Cyborg hit Diaz with bombs and the champ didn’t flinch. Diaz hit Cyborg with his patented pitter-pat straight punches and Cyborg looked prime for the slaughter. By the time the Brazilian muddled through a trip takedown with just over 30 seconds left in the round it was like you could hear the audience collectively muttering, “That may not have been the best idea.”

And it wasn’t. As soon as things hit the ground, Diaz made it look like all that stuff he’d done on the feet was just a goof. On the mat he was leaps and bound beyond Cyborg, taking all of 20 seconds to hook up an arm bar from the guard, grab a leg to flip Santos over and stretch him until he tapped. Then Diaz strolled calmly to the chain link to hand out his “fuck yous” for the evening, even throwing his mouthpiece into the crowd. When you consider that the object of his rage wasn’t rival Jason “Mayhem” Miller or prospective No. 1 contender Paul Daly, but reportedly just some random dudes who’d been yelling mean stuff at him from cageside, you get the idea what kind of guy we’re dealing with here. It’s also why a lot of people love him.

Diaz is certainly in a different marketing universe than uninspiring 185-pound champ Jacare Souza, who got rocked late in the first last night only to retain his title with a second-round choke-out of Robbie Lawler that felt more frustrating than anything else. As unstable as he is, Diaz is still definitely better for the sport than “fight ambassador” Herschel Walker, too. Walker looked decent in dispatching Scott Carson on the undercard, but without any kind of context for his no-name opponents it’s impossible to tell how seriously (if at all) we should be taking the former football player. Dare we say Diaz is more useful to Strikeforce than even Fedor Emelianenko who, if the company’s plans for its heavyweight GP work out, could finally see his first relevant action in nearly five years during 2011.

No, when you consider Strikeforce’s other legitimate promotional commodities: Alistair Overeem, who’s been most notable in the company due to his long absences; Gilbert Melendez, who is good but so starved for competition that Coker has to borrow guys from Dream and K-1 just to give him a challenge and Fabricio Werdum, who is yet to prove he’s not a one-hit wonder;  it’s clear that Strikeforce needs Nick Diaz more than Nick Diaz needs Strikeforce.

It also gives you a clue why he seems to have the upper hand in all of his negotiations with the company and why he chose to re-sign with Strikeforce recently. It’s good to be Nick Diaz right now, you guys.