LAS VEGAS -- I knew I was in trouble when I heard my ribs crack as the air slowly left my body.

I'm on my back on the second floor of Randy Couture's Xtreme Couture MMA gym, wondering whether the last image I would ever see is the smiling face of MMA referee Jason Herzog as he leans on me and applies more pressure to my chest. From afar, I did not appear to be in the most devastating position a UFC fighter could be in, but I am not a UFC fighter. I am an out-of-shape journalist who would find out later that I had torn the cartilage in my ribs while realizing how little I knew about the sport I have been watching for the past 15 years.

As I struggle to get up from the ground, legendary MMA referee "Big" John McCarthy, who was at one time as synonymous with the UFC as the Octagon itself, gives me a hand as I make my way back to my seat. McCarthy is in Las Vegas leading his popular three-day referee and judge training course called COMMAND (Certification of Officials for Mixed Martial Arts National Development). I am one of the 30 students in the class because I think I have what it takes to be an MMA referee and judge. Then again, I thought I would get through the class injury free and, well, that did not turn out so great.

"I promise I will fail you," McCarthy tells the class before some students have even had time to take their seats. "I owe it to the fighters. I will not put someone in that cage that doesn't know what they're doing."

"Big" John McCarthy, one of the pioneers of MMA refereeing, speaks to the class at COMMAND. Joe Amon for ESPN

McCarthy is standing in the front of the class alongside MMA referees Herzog, Jerin Valel, a former MMA fighter who has been working with McCarthy for the past nine years, Mike Beltran, a former McCarthy student who is famous among MMA fans for his long, unique facial hair, Mike Bell and Marc Goddard. As he paces back and forth, McCarthy looks over the class and stops in front of Amir Rahnavardi, who had a 12-year career as an MMA fighter and now wants to be a referee and judge.

"We want people to fight, not be warriors," McCarthy says. "Your job is to protect the fighters. When they can't protect themselves, you do. Our job is to protect the fighters! I don't give a f--- if the fans boo or don't like me. I don't give a f---. I have to do what's right."

There was a time when there was no right or wrong in mixed martial arts. In fact, when the very first UFC event was held 25 years ago, the company boasted there were "no rules, no scores and no time limits."

McCarthy was a spectator at UFC 1 on Nov. 13, 1993, at McNichols Sports Arena in Denver. He was a student of Rorion Gracie and served as his bodyguard for the night as well as a sparring partner for Royce Gracie, who went on to win the eight-man, $50,000 tournament. It would end up being McCarthy's last UFC event as a spectator.

"I became an official after UFC 1," McCarthy said. "Actually, the very first fight at UFC 1 got me my job to be an official."

Gerard Gordeau, a kickboxer, fought Teila Tuli, a sumo wrestler, in the first UFC fight, and Joao Alberto Barreto, a Brazilian black belt who trained under the Gracie family, was the referee. Tuli charged Gordeau early in the fight and was pushed to the ground. Gordeau then kicked Tuli in the face, sending a tooth flying out of Tuli's mouth, and followed up with a right hand before Barreto stopped the fight, which he wasn't supposed to do since there were technically no rules.

"Barreto comes in and stops it and you'll notice there's this argument between Rorion Gracie and Barreto, and basically Barreto is saying this guy can't fight and Rorion is saying you can't stop it," McCarthy said. "It was then when Rorion turned to me and said, 'I need you to referee fights for me.' I had never been a referee before. He said my qualifications were that I know everything people are supposed to be doing. I know the ground, I know the stand up and I don't mind seeing people get hurt."

McCarthy's career as a referee was almost over after one night. After UFC 2, McCarthy understood what Barreto went through during the first event. He simply could not stomach being inside the Octagon as someone was getting unnecessarily beaten without the ability to step in and stop the fight.

"After the first one I said I would never do that again," McCarthy said. "Some of these fighters didn't know how to fight this way and their corners were too stupid to protect them. The corners were told by the fighters not to throw in the towel, so they didn't, but I have a fighter who's mentally hurt to the point they can't continue. I told Rorion, 'I can't do that again. I'm not going to stand there while a fighter is getting his head stomped in and I can't stop it because his corner is too stupid to throw in the towel. I can't do that.'"

McCarthy convinced Gracie that referees could stop the fight if the fighter could not "intelligently defend himself," which was a rule added before UFC 3. McCarthy suggested rules after almost every UFC event in the early days as the rulebook grew from one sheet of paper to what it is today.

"I remember Tank Abbott was fighting Oleg Taktarov at UFC 6 and he put his finger in Oleg's mouth, and my dad did that in a fight one time and he told me, 'That's fish hooking -- don't ever do that,'" McCarthy said. "So I'm a little kid and I knew that was fish hooking and you don't do it, so I went to Bob Meyrowitz who owned UFC at the time, and I said, 'Bob you can't have this. The defense for this is to bite. You can't do that.' So he said, 'OK, no fish hooking or whatever you're calling it.' After UFC 7 I said you can't place your fingers in any orifice or cut. We had a guy named Joel Sutton fighting Geza Kalman and he head butts him, which was legal at the time, and he sticks his fingers into his cut and pulled down. It was ugly."

MMA referee Jason Herzog speaks to a group of students in Las Vegas in July. Joe Amon for ESPN

While the rulebook would be expanding before each event, McCarthy never knew whether there would be a next event. It always felt like the next UFC event would be the last until UFC 40, which was headlined by Tito Ortiz and Ken Shamrock and sold out the MGM Grand Garden Arena in Las Vegas and drew a gate of over $1.5 million.

"That's when I knew it was going to make it and was going to stay," McCarthy said. "People are starting to understand it and get it. It's a real sport with real rules that is finally getting some attention."

Every moment in life, good or bad, can become a teachable moment. That moment for me came when I tore the cartilage in my ribs. I found myself on my back after a conversation with Herzog on when to stand fighters up when he realized I had never actually trained in mixed martial arts. He put me on my back and applied pressure from a side control position. It was the kind of position I would yawn at if I were a fan and hope for the official to stand the fighters up, but then again, I had never been in that position before.

"You were in a position where you felt pressure from side control and it immediately changed your perspective on side control," Herzog said. "If you're in there and you don't know the basics of positions and what they do and when a person is in trouble and when they're not in trouble and more importantly what they need to do to get themselves out, you're not doing those fighters service and you're not doing yourself service. If you don't understand from a bare minimum what they're doing in there, that doesn't translate into you doing a good job as an official."

MMA referee Jason Herzog demonstrates a submission attempt with Arash Markazi. Joe Amon for ESPN

It would have been nice to learn that lesson without injuring myself, but sometimes you need to touch the stove to know it's hot. The truth is, it didn't take long for me to realize I was in over my head in the class. The way I watched fights as a fan was completely different than the way you must watch a fight as a referee or judge.

"If you're writing while you're judging, you're missing the fight," McCarthy said. "Action doesn't mean anything. We don't give credit for defending. We give credit for offense. If it has impact, it scores. Motion doesn't mean contact. So what if he's throwing punches? What is he hitting? What was the impact? Who did the most damage? It's about domination, damage and duration."

Suddenly everything I thought I knew about the sport, I began to second-guess. Whenever I'd see a bloody fighter in the cage, I'd automatically think his opponent was in control and had the advantage. Not necessarily.

"Blood is colored sweat," McCarthy said. "A cut is not a big deal. A small cut can cause you to bleed. It doesn't mean anything."

I was usually the type who would be upset at a referee for stopping a fight early or not allowing a fighter to fight through an injury without fully realizing what the fighter was doing to himself. McCarthy throughout the course continually stressed the responsibility the referee has in protecting both fighters.

"This is not about you," McCarthy said. "There are times where you're going to take the blame for things when you did nothing wrong. If it's you taking the blame to protect the fighter, take the blame. Do what's right for the fighter. It's not about making the fans happy. It's important for the official to have compassion for that fighter and compassion for what they are going through. It's your job to take care of them."

When McCarthy started his twice-a-year course back in 2007 in his hometown of Valencia, California, he did it so other referees didn't make the same mistakes he made when he was rewriting the UFC rulebook. Over time, the students in his course has evolved from fans to boxing or kickboxing officials trying to get more familiar with MMA to his current clientele, which is a mix of trainers, former fighters and coaches, as well as current referees and judges who want to learn more.

"When you think you know it all, quit," McCarthy said. "No one can know it all. There's always going to be something you haven't seen or heard before. The sport is evolving so fast, you must either evolve with it or fall behind."

"I don't give a f--- if the fans boo or don't like me. I don't give a f---. I have to do what's right." 'Big' John McCarthy

COMMAND isn't the only referee certification course available, but it's one of the most popular. The class typically reaches its 20-person maximum with more participating in a separate judge's course.

While most people in the class probably dream of being the next McCarthy, working the center of the Octagon for a big UFC pay-per-view, the truth is most referees will be doing smaller shows in gyms that seat hundreds rather than thousands of fans, just lucky to be making hundreds rather than thousands of dollars. Referees usually have a full-time job outside of the cage that pays the rent while they try to book as many officiating gigs as possible, often paying their own expenses to get to each event.

"I've been able to make money being an official but I've been doing this for 25 years," McCarthy said. "You're not going to get rich doing this. You'll probably spend more money than you make during the first 10 years."

One of the bigger names to become a COMMAND certified referee and judge is UFC Hall of Famer Frank Trigg, who sat in on our course. Few fighters have seen and done as much as Trigg in the cage, but McCarthy is cautious about putting him in certain situations as a referee.

"I've had athletic commissions ask me about my students," McCarthy said. "The state of California has wanted to put Frank in certain situations and I've told them, 'Don't do that yet. Don't give him that fight yet.' I'm doing that because I'm protecting Frank. It's not that Frank can't handle the fight. He can, but if anything goes wrong, people will eat him alive and he doesn't deserve that right now. He needs repetitions. He needs more time. He'll get to a point where he's ready for that main event."

There are three components to COMMAND certification. At the end of the course, McCarthy expects you to be able to talk techniques with him and his instructors. Can you watch someone striking, grappling, wrestling or applying a submission and be able to name what the technique is and what it does?

"We need you to be able to speak the language," Valel said. "No one wants to go to a doctor that says the whatchamacallit next to the thingamabob. Can you speak the language?"

Jerin Valel speaks to a group of potential MMA referees at COMMAND in July. Joe Amon for ESPN

The next part is knowing the rules and fouls of the sport and being able to apply past precedent to situations you are faced with.

Last is the practical component of watching and scoring fights for judges. While judging can be subjective, instructors want to know if you are able to score a fight correctly and are "within the acceptable tolerances." Referees, meanwhile, are put in the cage with fighters and are scored on their positioning and ability to properly officiate a fight. You must get at least 90 percent on each component in order to pass the class. In general, no more than a quarter of the people participating in each session reach that mark.

"Do you want your airline pilot passing with a C?" McCarthy asked. "I owe it to the fighters to fail you if you don't know what you're doing."

A man of his word, McCarthy happily failed me after my three days in his course because, frankly, I didn't know what I was doing. I could only name a fraction of the 114 techniques I was shown, I didn't have a full grasp of all the rules and fouls and I was a step slow getting in the proper position in the cage as a referee and handing in my scorecard as a judge.

While my dream of being an MMA referee or judge may have died as so many dreams do in Las Vegas, it will be hard not to watch a fight -- and certainly someone in side control -- without a newfound appreciation.

"Everybody who takes the course wants to pass, of course, but don't feel bad if you don't. I hate failing people, but I fail everybody," McCarthy said. "I want you to leave knowing more about the sport of MMA and more about what's important for the officials than you ever knew in the past. If you get that, then I've done my job."