At our last Yoshukai Karate Tournament of Panama City FL, I was asked to judge the Grand Champion Black Belt kata competition. The winners of 5 divisions - open hand or kobudo were competing against each other for the Big Trophy...
Among them was a talented young man who performed a remarkable open hand kata. I do not remember whether he won the price or not. All I know is that he should not have, and that I had know this from the first 2 seconds of his kata.
How can I decide such thing so early in the kata ? Very simple, when this competitor bowed before beginning his otherwise brilliant kata, his toes went up from the mat.
This is enough, if your toes go up, your weight is on your heels, a 5 years old child can push you backwards, and you will either fall down or have to step back.
From the moment you begin your kata, you should be totally focussed, and not let any opening for a potential opponent. When your toes go up, you are totally vulnerable. This demonstrates your lack of awareness and fighting spirit. No Zanshin. Poor Budo.
For your information and pleasure, look a this picture of Choki Motobu, performing a block found in our Yoshukai and Chito Ryu Nijusichi no kata.
Notice the Kibadachi stance, and how the joints of his toes are white. He is very strongly gripping the floor with his toes. Choki Motobu's idea of a good training session was to go down to Naha's entertainment district and pick fights. He was a born fighter and his karate was based on actual fighting. If anyone knew the importance of proper stance and posture, he was this one...
It does not matter how good you are with your arms. If your balance is poor, you won't have any power and you are only generating wind. Weak stances do weak Karate. Grab the ground.
Oh, and while I am at it, I believe this also applies to Zazen. Stay Grounded.