In the late 60's, Iowa got really good, with Ed Podolak and other quality players, and were really close to being a ranked team in 1968 if they hadn't lost a couple of close ones that year (they were 18 points away from being 8-2). Evy was AD at the time, and he didn't get along with Nagel (or, really, anyone).
Then in Spring 1969, two black players were kicked off the team (academics for one, rumored the passing of bad checks for the other). Now, this was when there were campus protests at Iowa, and the Black Power movement was occurring, so tensions were already high. So after those two black players were booted, sixteen other black football players threatened to boycott practices until the two kicked-off players were reinstated. Nagel said they'd better come to practice or they're off the team, and that was that: they didn't show, so he booted them.
The suspended black players then sent a red-hot manifesto (which included some unfortunate slave-master comparisons) to the papers, which further dis-endeared them from Coach Nagel. A short while later, some of them had a change of heart and wanted back on (realizing they may have been manipulated by others with their own agendas at the time), but I recall that they were told no, it's too late now, we'll have to vote on you in the fall for reinstatement (and some actually were let back on the team). However, this really soured Nagel on the whole Iowa FB experience. And on manifestos, too, I'd bet.
Meanwhile, Evy and Nagel were in full warfare mode with each other, to the point where a FB assistant complained to Evy behind Nagel's back, and actually started spying on Nagel, and it all blew up: the freshman coach quit, taking his starting QB son with him; the asst coach-spy was fired by Nagel; then Evy AND Nagel get fired; then Nagel is reinstated; then Nagel quits for good a couple years later since the program was destroyed by all this craziness; and a team with a lot of promise in 1968 got bad enough to end up 0-13 in 1973 under FXL. Attendance got as low as 31,000 for a game that season. The absolute worst year in Iowa FB history.
Is it any wonder we got terrible after all this crazy shit happened?