The conversation about learning from someone you can beat stemmed from the example of Bruce lee teaching other champs like joe lewis and chuck norris. Obviously Bruce was fast, had much power and technique so on and etc. Now given that he possessed these attributes if he could have been beaten by Chuck or Joe then it was because of flawed technique. Also I think any good teacher should be able to fight better than his students because he has more experience and a better understanding of the system. Shoalin Monks fight even in their late sixties and probably even older and are quite confident in doing so.