This is a very interesting piece...especially the snippet of Geno demonstrating the proper defensive stance. I remember Pat Riley saying that was the first thing he wanted to see from anyone trying out for the Lakers...if they didn't have it down, he wouldn't look at their two-handed reverse dunk.
I've spent many years studying what you know as Shaolin Kung F*...the art famously practiced by people like Bruce Lee and Jackie Chan. It too has fundamentals that have evolved over several thousand years, and the most basic one is the Ma Bu Stance...also known as the Horse Stance. It looks like this:
When my teacher learned the art from a former Shaolin temple student, he was made to practice this stance for 6 months before he was taught any additional techniques. A proper Horse Stance will have the feet pointed forward, thighs parallel to the floor, with the buttocks pushed out, and the back "arched up" to keep the upper body from leaning forward. Some styles teach keeping the buttocks tucked in which is a more relaxed position so not as good for training purposes.
The reason for the emphasis on this stance is that it is considered the foundation from which all power is generated in the empty-handed arts. The practical aspect is that when you can sit in this stance comfortably for long periods of time, your ankles, knees, quadriceps and back become very strong. If you believe the folklore, the internal organs strengthen, as well. That beneficially affects your quickness, agility and speed; while providing the best preventative against problems like the high ankle sprain, the lower back strain, and the dreaded ACL. And it has the benefit of being practiced without the necessity of a gym, weight room...you don't even need shoes.