https://www.espn.com/college-football/story/_/id/35359074/inside-sidelin...

The above story has some nice anecdotes about how paranoid coaches are.   Knowles and Leach are quoted extensively.  I'm honestly amazed that teams haven't pushed to provide their own ball boys, and make the NCAA/conference provide the chain gang.

Not only is Knowles convinced that opponents have filmed his signals, he believes some teams will then turn around and share what they've learned with others. "The enemy of my enemy is my friend, right?" Knowles said.

Knowles said he doesn't like to talk about it because what can he really do to stop it? But since he was asked, he wasn't going to pretend it wasn't real. "It is a huge part of what goes on," he said, "and kind of a story behind the game."

"You know," he said, "if you can imagine it, it can be done when you have resources and people and time."