Two of Lou's starters on the offensive line were good friends of mine in my undergrad days, They were a great source of knowledge when it came to knowing what proper mechanics were, what body types, flexibility in various areas (especially hips), as well as football smarts, etc., and it wasn't just limited to offensive linemen. They had pretty deep levels of knowledge on what made players at each position good ones.
They were always happy to share insights on various players, since they saw a lot of video footage of other players, both ND and opposing ones, and this was in the days before the internet became widespread, much less having video sharing sites.
Sometimes, we'd all watch games that someone had taped and they could point out how certain players lighting up the stats in those college games, as well as those who managed to attain all-American status, would be big busts in the pros, and they were almost always right, that their analyses of these guys led to the conclusion that they were one or two trick ponies.
They could also point out who the best technicians were at all positions, and not surprisingly, a lot of those excellent technicians ended up getting drafted, even if they weren't superb athletes.