Drezner's proposal is that "thought leaders" are narrow but deep, usually evangelizing one big idea as the solution to our problems and that public intellectuals are broad and that their role is in pulling apart and critiquing the big ideas of thought leaders. As I understand it he believes that big money is putting their thumb on the scale so that we've lost our balance between the two. Lots of bad big ideas floating around with not enough discourse about why they are bad.