This post is interesting. Not that my opinion matters much, but I find merit in Hogey's and AM's arguments.
Hedge is right to say you should be versed in a good grappling style, like wrestling (preferably freestyle or catch), Judo, Shuai Jiao, Tegumi (only some know this nowadays) or GJJ/BJJ. When I say versed I mean you should have a good fundamental understanding of how to stay on your feet, reverse a mount, keep someone in your guard and how to submit someone if the fight does go to the ground. This doesn't mean you need to be first kyu or higher in Judo or a BJJ Purple Belt or > (although that wouldn't hurt). It means you should understand some basic principles that apply to standing and ground grappling.
In a one-on-one confrontation an art like GJJ can be very effective. I don't know how you'd be sure that there is only one opponent involved, but if you are doing sentry disposal or are a SpecOps guy who confronts an enemy soldier down some dark corridor, it would help to know how to choke him the f-ck out! In the streets of most major cities around the world, friendly mano-a-mano matches are very unlikely. Maybe on the beaches of Brazil, but not anywhere I've lived. If someone attacks you on the street always assume that there are multiple attackers just waiting in the shadows. In this instance even getting a knee-on-chest mount is not safe. BTW I have seen the knee-on-chest mount from folks who were not formally trained in anything. A strong cat that understands his strengths will often employ this tech against a oblivious and often weaker opponent. I've seen it twice in my college days and twice when I was in HS in the mid-80s. This was way before anyone where I was at knew about GJJ or groundfighting. In a "fair" fight it is a good position to be in. In the streets it's just as dangerous as the full mount or the guard.
For those martial sport types who claim that you can't defeat multiple opponents on the street, I say what's your evidence? I have seen it multiple times, and even an instance where 3 guys back-to-back in a club fought off dozens of idiots rushing them from all sides. Know that only a certain number of dudes could get at them at one time. The sheer number of folks involved in the fracas shielded the three guys from the other attackers. They clocked suckers rushing straight in, punted a few, threw a lot (the three were all big football players) and didn't stop striking and moving as one mass. In the end the cops came and all that happened to the attacked was one guy had a "shiner" under his right eye. I don't need any proof that fighting multiple opponents can work. I've seen it.
I saw the same guy who used the knee-on-chest mount, we called him P.S. (for Pitiful Specimen), beat three policemen severely after they tried to punk him at a BBQ stand outside the Maingate of Clark AB, Philippines. He didn't know any MAs, just football
, but his pops was a big Combat Controller who could bench like 600 pounds. This kid was about 70" and 180 pounds. Not a brute by any stretch of the imagination, and actually someone who we considered on the lower end of our crew's hierarchy, in physical and mental toughness. He was 18 when he kicked the SPs asses and then ran back on base before they knew what even hit them. It was hella funny!
On to AMs assessment of real fighting. You better have a good foundation in street fighting or a good MAs foundation in all ranges of combat. Sure you can be a karate-ka or TKD cat with awesome striking skills, but if you don't end the fight fast you better know how to choke someone. In order to choke someone you have to get them, or better yet you have to let them get theirselves into a position to choke them. Hand chokes as found in styles like Kuntaw Silat, Karate Jutsu and Eagle Claw Chuan Fa are the best for the street. Rear naked chokes are good, but they take sometime to act on the opponent. Constricting the carotids can be done much easier with a grasp of your hand. Pure grapplers better understand that if 90% of fights end up on the ground, then almost all fights (99%) start out standing. Learn to keep it here. Learn to punch without padding and with a good understanding of biomechanics and A&P. This takes years of bone, muscle and sinew conditioning. You don't get that from hand wraps and gloves. You get that from Ktoeate/kotkitai and other "iron body" exercises. Hiting a heavybag as hard as you can without gloves is the beginning. Moving on to makiwara and other hard objects polishes this skill. Kata conditions the sinews. Two-man drills done full force makes your weapons and your body strong without causing brain damage and unnecessary injury.
Weak bones come from years of wrapping pillows around your hands and feet. If you break your hands how will you grapple or punch? This is what the BJJ guys don't understand. This is what the very deadly ring tacticians like boxers and Thai Boxers have forgotten with the advent of more and more rules.
As for animalistic fighting traits. All the bestial instinct in the wolrd will not save you from someone who is more animalistic, bigger, faster, stronger and more intent on getting at you than you are. Being strong from weight training, being able to absorb blows and remaining calm with the undercurrent of brutal intentions takes years of training and practice. TOMAs address this well, as do good Chuan Fa styles and even good Japanese karate styles like Kyokushinkai.
What I've seen is some gain this "animalistic" ability from getting stole a lot and fighting on the street. Others get it from hard sparring and intense training. Some acquire it from having their older bros, moms and pops kicking that **** regularly.
It is not innate, it is conditioned like every other habit or learned "trait". So no matter how many years you practice rape safe or Animal's **** Saving SD, you just are not gonna ingrain that type of attitude and stance. It comes from misfortune, training and practice in entropic situations. The killer instinct is cultivated and not innate. An example is the fact that research shows prior to Vietnam the troops trained to be soldiers, not killers. As a result studies have shown that only 10-15% of the troops on the ground in WWI-Korea actually fought! The rest cowered, hid under dead bodies or ran like beyotches. After this problem was identified the Army and Marines changed their training from a chivalrous stance to that of sociopathic killer school. You have to kill the conscience to a certain degree so that when it comes to life-or-death preservation you take the opponents life and spare you and your buddie's own.
You know, if you fight on the street with the intent of winning through technique and restraint you've already lost. If someone attacks you on the street you have to think "this dude don't know me, he obviously wants to kill, rape or maim me or mine" and act accordingly. Deal with the litigation later. It's you or him/them. If AM is teaching this type of training it is more suited for protecting your neck, but no moreso than training in good combat sports like Thai Boxing and BJJ.
In the streets a GOOD TMAs type has just as much chance to be victorious as a PROFICIENT MMAs cat does. Intent, EXPERIENCE, LUCK and mindset are what set apart the victimimized from the victorious, in a street situation.
If what you do in your combat sport (like Gracie Self Defense Techs) or your Animal fighting ingrains true intent then it will be more effective than patented TMAs and MMAs theory. That's MY facts, Jack!
Peace.