A lot of the aikido teachers who do "interesting stuff" but can't explain it, learned by hands-on transmission... by "feel." Many old traditions in Asia were, and still are, taught this way. Very little descriptive terminology or systemic training, and mainly the teacher letting the student feel and eventually imitate, and inculcate, through touch.
So, it's not surprising that individuals with these skills don't know how to explain or describe what they are doing. I have had this experience as well. It takes integration between Eastern and Western teaching methods to arrive at a system that methodically teaches internal skills. A few have done it and are getting very good results from it.
That's so true.
I would have liked to meet Dan for the first time on a seminar earlier this summer here in Germany. Due to unforeseen snags arising, the event had to be cancelled. Luckily, I was able to meet one of his (not so longtime) students. We played a little bit around and he repeatedly stressed that all he could show me was only a pale shadow of Dan's abilities. But nevertheless, since I have felt this student I'm quite convinced that Dan has excellent methodology and teaching ability.
So my conclusion, there are (and will be) also people, who can teach and explain this stuff in an all out systematic way.