I know a Judo Chop of Georges St. Pierre's takedowns of Alves from UFC 100 are a little dated, but they're absolutely still worth a look not just because they helped carry St. Pierre to victory, but because they are evidence for the notion that St. Pierre has the best takedowns in all of mixed martial arts.
First, it's worth noting that while St. Pierre put on an incredible display of takedown aplomb, he did not take down Alves at will. The American Top Team product was able to shrug off several takedown attempts throughout the course of the fight, which is a testament to his skill and preparation for this historic bout.
Second, what makes St. Pierre so special is that just like high-level BJJ players link together submission attempts in "chains" to increase the likelihood of landing a submission in competition should one or two or even three attempts be avoided, St. Pierre puts together chains of takedown attempts. Admittedly, others already do this in professional MMA, but almost always they do so when trying to takedown an opponent whose back is pinned against the cage. From that position, it's far easier to transition from a double to a high crotch because the opponent is being driven into a wall and doesn't have enough mobility to resist. St. Pierre is able to switch from one type of attempt to another without the help of cage in free space. Working in open space while transitioning requires impeccable athleticism and timing and is indicative of the unique level of skill St. Pierre brings to professional MMA.
Earl from D-1 College Wrestling (a site I cannot recommend enough) adds some helpful context about what makes St. Pierre's takedowns in this fight so special:
These clips show that GSP can consistently finish takedown attempts on a large, powerful opponent in Thiago Alves. Many fighters will attempt takedowns and get stopped, but GSP’s ability to finish is the result of his excellent technique.
In each clip the common theme is GSP’s foot movement. He never stops driving, even if he is initially "stonewalled". If he stops driving his feet, Alves has the opportunity to sprawl and stuff the attempt. In wrestling, the shooter is often taught to shoot a double leg as if he is "shooting through two or three opponents". Aiming for "just one" opponent may lead to the shooter stopping when he makes contact with the defensive wrestler.
Another technically sound portion of GSP’s takedown offense is the fact that he actually is shooting on Alves. Often you will just see a fighter just dive at his opponent’s feet with his head down. This is much easier to defend. A trick that I was taught when shooting on an opponent’s leg is "Never let your shoelaces face the mat". Obviously these fighters are not wearing shoes, but the point remains the same. You do not want to be sitting on your feet with the top of them facing down. In this position, you likely are overextended and carrying the weight of an opponent who has already sprawled and it is difficult to generate the power needed to finish the shot. In each clip GSP never lets this happen.
It still blows my mind that GSP is such an incredible wrestler, yet he never was a wrestler.
Let's break down the more notable takedowns after the jump.
In the first takedown, we see St. Pierre attempt to run the pipe off of the single leg only to switch to a double leg to finish. When running the pipe to finish the single, you're circle your back leg clockwise or counterclockwise (depending on which leg it is, but the motion is always to the rear) while you pressure your chest down on the thigh of your opponent. This forces them off balanced hopping on one leg while you drive them down. In this instance, St. Pierre attempts to run the pipe, but a strong Alves resists. Sensing he can't get Alves to the mat off the single leg alone, St. Pierre uses Alves' balancing leg - also the supporting leg - to transition to and subsequently finish the double. A double, mind you, that's aided by St. Pierre changing angles on the takedown at the last push. This is an impressive, athletic feat and one St. Pierre has likely drilled under the tutelage of the world-class wrestlers on the Canadian national wrestling team (and the others he trains with).
In my view, this takedown is the most impressive of them all in terms of demonstrating St. Pierre's immediate adaptive capability. Here we see St. Pierre penetrate deep on Alves' hips, but the ATT product was prepared and immediately dug underhooks and forced his hips out to rip St. Pierre off of him. However, St. Pierre immediately feels Alves' resistance and quickly goes from low to high by switching from an attempted double on Alves' hips to a knee tap on Alves' right knee/left armpit. St. Pierre blocks Alves' left knee while he "throws him by" and drives Alves to Alves' left with the underhook from St. Pierre's left arm. Again, note how rapidly St. Pierre changes his attack once he feels the strong resistance from Alves. It's takedown sleight of hand: get the opposition to commit to defending a takedown that you're not actually attempting.
To Earl's point, here's another perfect example of St. Pierre continually moving his feet and driving through until the takedown is finished. And, once again, notice how St. Pierre changes angles when he drives. Some folks think the double leg is accomplished when you drive straight back and off balance your opponent through sheer momentum. And while that can work for a scoop double (like the kind Fedor Emelianenko prefers), the reality is you have to finish the double in most cases by driving in a perpendicular angle from the one in which you penetrate.
For those curious about how to properly run the pipe:
And then Tito Ortiz explains how to land a knee tap takedown, albeit from a slightly different position: