Innovation must be top-down and bottom-up simultaneously

It’s telling that this BusinessWeek/BCG survey only lists executive titles in this answer, even as executive-focused publications like HBR are publishing articles telling us, “Because so much of the learning about customers and so much of the experimentation with different segmentations, value propositions, and delivery mechanisms involve the people who regularly deal with customers, it is essential for frontline employees to be at the center of the customer-centric innovation process.” Which is it, top-down or bottom-up?