First of all, you do not want Scott Frost or Eric Crouch anywhere NEAR the teaching of quarterbacks how to pass. Great competitors and leaders, but even as seniors they didn't seem to grasp the basic fundamentals or mechanics of passing. That Frost has become an astute defensive coach suggests Bill Walsh was right.
Keep in mind that while Scott Frost was a small town Nebraskan, his father had played for Devaney/Osborne and his mother was an all-American track star at UNL. If there was a "diss" to the program, it was by a couple savvy parents and UNL sports alums. In fairness to them, when Bill Walsh comes to your kitchen table in Wood River or wherever and offers a scholarship to one of the finest academic universities in the country, your loyalty to your son might weigh heavier than your loyalty to your state.
I think there was also some scuttlebutt that Mr. and Mrs. Frost did not think UNL was giving Scotty enough love and/or had some older slight they held against the athletic department.
And since we have a thread with Bill Walsh in it, might as well point out yet again that the WCO was never a pass-happy offense. It was designed to be a high-percentage offense. And the legion of coaches who went on to adopt and fine-tune the WCO would be perfectly happy to have 200 yard rushing days if that's what's clicking