My grandfather told me
that a lot of it was over the offense he ran. I can't remember if he ran the single wing, the double wing, or whatever, but apparently our fans or a large group of them wanted him to change to something more modern at that time (wing-T?) and basically ran him off and the indians became angry and forced us to suck while Ole Miss had Vaught until we broke the curse by hiring Bob Tyler. He didn't say anything about any particular booster. He made it sound like it was the President of the University and some of the deans that were behind it- and they may have been influenced by a booster, I don't know.
Anyways, whomever replaced McKeen- I think Slick Morton changed the offense and it was an epic fail.
My grandfather would know since he took a train to watch us play in the Orange Bowl and was in Oxford when we won the SEC Championship.
I did ask him why it took so long for MSU to be good in football after that and he said it was because in the 50's and 60's the engineering people and the ag people at MSU couldn't agree on a particular coach and one side would support one coach and then when that coach didn't win, the other group would support the new coach, but the other wouldn't.
Basically, we were an unmitigated cluster17.