This would be related to 'Theory vs. Practice', 'The Devil is in the Details.', and 'It looks good on paper.' It particularly fits the subject of politics. 

I remember when I was first a college student at the University of California at Santa Cruz as a Political Science major. The university just shortened the major to Politics, which was not a bad idea, as politics has very little to do with science. As a 20 year old I was in awe of all the PhDs after my teachers' names. I figured they surely must know a shitload about politics. I didn't return to college for another 20 years. When I did I noticed an amazing thing. The professors sounded dumber to me now that I was in my early 40's. I finally figured out why.

While I had spent 20 years working a slew of crappy jobs where the only entry requirement was to make fog on a mirror, these professors had been holed up in their ivory towers, jumping through whatever hoops they must to gain tenure. I was rolling around in the mud on the fringes of society being exposed to 'realpolitik', while they were kicking around abstract political theories up and down the halls of academia. I was living a 'detailed' life. They were living a life of academic 'generalizations'. 

I recall one class I had with a professor who was at the very end of his career. I also had him 20 years before when he was in the middle of the batting order and at the top of his game. He had degrees up the ass, published extensively, and was very well known in academic political science circles. I remember one day in class a student challenging him on some point and he said, "Hell, I don't have a clue about half the stuff I say." It wasn't in a joking manner either. It was the voice of a man at the end of his work life who was tired of pointless, academic pontificating. It is one of the few things I remember from college.....