Jeff Farris
Although a coach can have a tremendous amount of knowledge about his sport, the two most important considerations for a coach are:
  1. Can he teach what he knows?
  2. Can he motivate his players to do what he teaches?
According to the Wikipedia, "a teacher is a person who teaches; a person who guides, instructs, trains or helps another in the process of learning knowledge, understanding, behaviour or skills, including thinking skills." 

Although a coach may have tremendous skills from playing sports, their ultimate success will come more from their teaching skills. Coaches who want to be successful must complement their playing skills with the necessary teaching skills. Otherwise, a coach who knows everything about his sport will often find himself losing to coaches who know far less if he cannot teach what he knows.