The 'plunk' you are describing is his ability to just 'get it done' - a trait I think most tech founders greatly underestimate. It's an ability or mental strength that makes a person able to will the project over the goal-line. I'm amazed how hard it is to complete anything - whether it's a startup app I'm working on or a piece of music - finishing it 100% and getting it 'in the can' is no small feet. It's special gift, and one that I would highly recommend anyone searching for a founder look for in their partner(s).
I have to admit I like Jeff, from his articles and such he seems to have a pretty clear way of thinking through big tech issues, and while he may sometimes surprise me with a 'lack of knowledge', I just remind myself that we all have gaps in our knowledge and at the end of the day, he's done some incredible work, and this 'lack' hasn't hurt him much (maybe it caused him to take longer to get to where he is, but he still managed to get it done).