My read on it is perfectionism mixed with a lack of organizational skills for writing with perhaps a heavy dose of the forest-view sort of gifted mind.
I love this description.
For skills, perfectionism, big picture thinking (and for many career endeavours) the key skill is organizing thoughts into bite size executable pieces. Start first with unstructured brainstorming of ideas, points, counter points. Capture those, organize them, hone them down and writing the most clear piece first (not starting at word one and end-to-end one word after another.) I'd look into helping him find graphical tools for organizing thoughts like thought maps.
This is why I've enrolled him in a summer writing program. I can't convince him to outline, make notes, or start in the middle. He needs help by someone other than me. He has been taught these strategies over the years. My husband isn't helping because he starts with word one and works to the end himself. And the fact that DS can get away without doing other things the teachers suggest like study for tests, make detailed outlines of the chapters doesn't help convince him that they are right on this.
