I actually met Jordan Cooper once.... and I've been a regular follower of his website since it went up. I know he got his doctorate on this very subject (from some seminary in South Africa)...
BUT.... I've never figured out WHAT exactly he means by "mysticism." Kind of goes over my head. And since I tend to think of this from the Eastern Orthodox (especially Greek Orthodox) perspective (as little as I understand that), well... it seems quite inconsistent with Lutheranims.
What I DO think is that for Luther and the Lutheran Fathers, there was a huge sense of MYSTERY. But they mean this (it seems to me) not in any sense of mysticism but simply of unanswered questions. Luther - especially as the years went by - became increasingly cautious of logic, philosophy, and really "answers" at all, ever more sensitive that God's Truth is true simply because it is God's. It means nothing as to whether we can wrap our puny, fallen, limited, human brains around it or not. This humility is what permitted Luther to accept paradoxes, to let Law and Gospel stand "as is" whether we can "understand" how they interrelate or not, why Luther could accept Real Presence, the Two Natures of Christ, etc. To Luther, these truths are true beause they are His Word, not because Luther could "make sense" of them. THAT I think is very "Lutheran" and I see this as part of the humility of Lutheranism. But I have a strong hunch that is NOT what Dr. Cooper means by mysticism.
??????
- Josiah