I think the middle ground between theory and practice has gaps in most areas of expertise. The problem may be that to create good content in those gaps one need

I think the middle ground between theory and practice has gaps in most areas of expertise. The problem may be that to create good content in those gaps one needs to have accomplished a certain level of skill in both areas, theory and practise. Very few people get around to actually step aside from their daily work (which usually is pure theory or pure practise) to achieve something on the other end, though.