Christian Petersen/Zuffa LLC/Getty Images

Nate Diaz surprised many people on Saturday at UFC 196 when he submitted the Irish juggernaut Conor McGregor in the second round with a rear-naked choke. He was an underdog going into the fight, and in our staff picks, we all picked McGregor to win.

Our rationale was that Diaz had been fighting mainly on the feet and that he wouldn't be able to withstand McGregor's striking. We were so wrong. McGregor's striking coach, Owen Roddy, told James Edwards of the Independent back in February that McGregor "hits like a middleweight." I don't know about the rest of the predictions crew, but I interpreted that to also mean he was used to getting hit like a middleweight too.

He was not. Nor welterweight. Nor could he compensate for Diaz's height and reach advantage, both new considerations in one of his fights. Although McGregor is the 145-pound champion and was originally planning to fight at 155, the bout with Diaz was fought at 170. There were many factors at play in this fight with which McGregor had not had to contend before.

One of the biggest factors was Diaz's blistering Brazilian jiu-jitsu. McGregor has faced BJJ experts before, but the Diaz brothers are known for their extensive and traditional BJJ games. For example, in this fight, we saw an inverted guard—a position rarely seen in MMA that's usually relegated to grappling competitions or Rousimar Palhares.

Diaz proved on Saturday that a solid Brazilian jiu-jitsu background is as vital as ever in MMA. He was winning on the feet, as well, and McGregor seemed rocked by the time he shot for a double leg toward the end of the second round. Even so, it was ultimately Diaz's Brazilian jiu-jitsu that halted the juggernaut's star-making velocity.

Video Play Button Videos you might like

And what jiu-jitsu it was. Seattle-based Brazilian jiu-jitsu black belt Tristan Matheson joined me to break down what happened.

Diaz said he expected the fight to go to the ground, so before the fight, I analyzed his and McGregor's grappling. The pertinent takeaways from that were:

McGregor shows comfort in top positions, although he rarely attempts submissions and instead prefers to strike.

He's passive and inactive in others, including closed guard—both in it and on someone else.

Diaz prefers to grapple from his back, and will readily go to the mat to get there.

While not a wrestler, Diaz has an excellent sprawl and uses it to snag guillotines.

The Grappling

Josh Hedges/Zuffa LLC/Getty Images

Sydnie: Toward the end of Round 1, Diaz caught a body kick and dropped McGregor simply by pivoting to his left. Conor got his hooks into butterfly guard and finagled a sweep.

Tristan: Diaz pretty much rolled himself over just so he could slap McGregor twice.

Sydnie: He did go along with such a blatant lack of concern it seemed like being swept was just as much his choice as McGregor's. Good choice, as it facilitated that Stockton Slap.

They landed right by the cage, ending up in Diaz's guard, right where he loves to be. Immediately, Diaz started to climb his guard up, opening his legs to do so.

McGregor grabbed Diaz's left ankle with his right hand, trying to collapse the leg and take away structure and leverage. McGregor stood his feet up and stacked Diaz, who raised his hips off the ground and allowed McGregor to drive his own hips forward. With his hips above Diaz's laterally, and with Diaz's back against the cage, his leverage was limited. McGregor easily pushed Diaz's right leg to the left and passed the guard, but only briefly.

Josh Hedges/Zuffa LLC/Getty Images

With his hips free, Diaz did a partial granby roll and recovered his guard. McGregor stayed there, striking, as Diaz worked underneath him. Initially, Diaz held onto McGregor's right wrist as he planted his right foot into McGregor's left bicep, probably in an attempt to set up a triangle.

When McGregor pushed his leg out of the way, Diaz rolled to an inverted guard with his legs around McGregor's body and hit him with a hammer fist while upside down. McGregor was on his knees in a wide base, and the round ended there. If it hadn't, Diaz probably would've gone for some type of leg lock.

After being outstruck in the second round, McGregor shot (on Nate Diaz!?) for a double leg.

Tristan: McGregor shot a lazy take down, which Diaz is used to seeing when he batters his opponents. Diaz sprawled perfectly. Since McGregor left his hands around the hip area, Diaz simultaneously, latched onto his overexposed neck like a lion on a wounded gazelle.

Sydnie: McGregor was on his knees here, and he stepped up his left foot and slid his right leg through the space created, which is called changing or switching the base and is similar to a wrestling sit-out. While McGregor was doing this, Diaz happily fell to his back, which is the progression for guillotines on the ground.

Tristan: McGregor, already in survival mode, did just the right thing: He jumped around to the correct side in hopes of an escape. But the jiu-jitsu ace had the perfect counter. He used the top of his foot as a hook to stop McGregor's right leg and movement from moving to top side control.

Sydnie: So McGregor's leg was trapped. He stepped up his feet, a common guillotine defense that sees you pitch your weight forward, pinning your opponent's head to the mat with shoulder pressure and taking away the leverage necessary to finish the choke. But with one leg trapped, his weight not fully forward and his balance not established...

Tristan: Diaz wrenched a high-elbow guillotine, a move made famous by Marcelo Garcia. As he pointed his elbow to the ceiling, it rolled McGregor over. At that point, McGregor's last chance to get out of the choke was to explode from his back and bridge out, creating a scramble that would land him on top or get him back to his feet—he did that very move against Chad Mendes [at UFC 189], and it secured him the win.

Sydnie: So McGregor continued rolling the direction Diaz sent him, which freed him from the guillotine threat.

Tristan: If Diaz had continued the guillotine, he might have lost position—like how Mendes kept going for it when it wasn't secure. Diaz saw it was going to be tough to keep, so he let go and was already thinking of maintaining position, whereas McGregor was thinking he was out.

Sydnie: Let me just quote myself from my pre-fight analysis here:

Against a wrestler such as Mendes, McGregor could capitalize on any space offered during guard passing and transitions and escape, but Diaz will be grappling with jiu-jitsu. And he is a high-level practitioner; his pressure and control of space will make escape attempts far more difficult.

Tristan: McGregor reached up to get his underhook, but Diaz sensed the urgency, and being the jiu-jitsu ace he is, he caught an over-under grip, around the arm and under the tricep to establish control. It stopped McGregor's momentum and landed the much calmer Diaz in side control—a position no one wants to be in on the bottom, especially an already battered, gassed fighter.

Sydnie: Diaz also shoved his right knee into McGregor's back, keeping McGregor on his left side and preventing several of the common defenses there. His left arm was under Diaz's control. McGregor couldn't roll to the right, which is where the defenses were available—he could attempt to shrimp out and recover full guard or try to get a knee in between his torso and Diaz's, for example.

So with the hips partially immobilized by the inability to turn to the right, Diaz was in minimal danger when he stepped over to take technical/S mount, with his right foot flat on the mat.

And here we saw a great example of Diaz's genius. The best type of full mount to have is when your opponent is flat on their back, and Diaz accomplished this by angling his shin across McGregor's torso, planting his right knee near McGregor's right shoulder—which was raised because McGregor was kept on his side in side control.

Diaz then forced McGregor flat on his back by putting his weight into that right knee. McGregor was totally controlled in every second.

Tristan: McGregor, much like on his feet, left his chin exposed. Nate unleashed a barrage of clean punches. McGregor's only move to escape was to bridge his hips and turn, but once again, Diaz could feel it. Basically, McGregor did everything right in terms of escaping, but Diaz was two steps ahead, so it didn't matter.

Sydnie: Diaz was high enough on McGregor that the Irishman could bridge and roll onto his stomach, trapping his own right arm underneath him as he did. While that escape attempt may have been the right idea, he didn't do enough to protect his neck. Diaz rode the bridge and secured what was essentially the ultimate position: rear mount on someone who's on their stomach.

Tristan: Diaz slipped both hooks in and did a beautiful job at creeping his arm into position for the choke. He then pushed his hips downward, causing all his weight to crush McGregor, much like jumping on the middle of an aluminum can. It caused McGregor to arch and look up, slightly exposing his neck.

Josh Hedges/Zuffa LLC/Getty Images

Sydnie: Diaz shot his right arm under McGregor's chin from the right, where McGregor's right arm is trapped underneath him. McGregor attempted to tuck his chin and buy himself some time, but Diaz answered with a quick left that turned his head.

Tristan: Nate slid the devastating mata leo choke in. It was already deep. The victory was secure. The Irishman was forced to tap or go to sleep, and jiu-jitsu prevailed once again.

Sydnie: From the moment Diaz closed up the choke, it took less than three seconds for McGregor to tap. That is one tight RNC.

Tristan: I don't think McGregor was inefficient with his energy. I think Diaz was just more efficient in his technique. When flash doesn't work, stone-cold basics prevail every time.

Sydnie: Yeah, I didn't understand what McGregor meant based on what I saw. It looked like he couldn't catch Diaz, the height difference made him work harder and he wasn't used to being hit that hard. Well, I suppose that is in fact highly inefficient; maybe McGregor just meant that his plan of attack, if there was one, was poorly conceived.

Brazilian jiu-jitsu is often referred to as mat chess and a game of inches. McGregor's grappling isn't awful, by any stretch, and he's demonstrated some very fluid and insightful movements on the ground, but Diaz's comprehensive understanding trumps McGregor's knowledge and abilities on the ground.

While the outcome might have been unexpected to many, that Diaz's grappling was miles ahead of McGregor's was best summed up by Diaz himself (NSFW audio):