Its interesting to speculate - Alan Jones was a good coach 25 years ago, and although he technically understood the game, I dont know that he ever even played it. His skills were in getting the players really fit, and choosing the type of players he wanted to play a particular plan.
Buchanan was a good cricketer by ordinary standards, but was ineffective in a handful of first class games. Yet he was a superb coach by any measure, except perhaps the players (mostly particular high profile ones) liking him. Buchanan's skills seem to line up with what Noddy expressed as a skillset in the first post.
To me, a coach should have:
1. A philosophy on how the game should be played - this is a broader concept than a "game plan";
2. An ability to identify and develop talent that is latent or unused in players, or that others have not noticed;
3. the character to play well with others, and delegate where necessary;
4. A passion for his team, not just for being a "professional coach".