I don't have much to add to BGIFs usual solid retelling of history. Devine's era was WAY past my time. These are the things that i remember:
A). He followed Ara and wasn't a "public" sort of person. He therefore seemed a bit "distant" to the fans, who therefore couldn't become affectionate towards him. We all know Ara and Lou with affection not because they won football games, but because they were, in their different ways, likable media personalities on top of that.
B). Notre Dame nation were a bunch of spoiled brats [we have never fully lost this characteristic, but recent times have been, in that one way, helpfully humbling]. The shallow fans were demanding NC challenges every year---no excuses. After the furor of his initial hiring [they weren't sure that this "Missouri guy" was right for Notre Dame], his first two years shut most people up. The 1979 season was, however, H*ll-on-wheels. We finished 7-4, losing to Purdue early [a MUCH bigger deal then than now] and USC in the middle [always hated]. Still, things might have been tolerable, but late in the season we lost, in a shellacking, to a mediocre Tennessee team, and then closer to a mediocre Clemson team. Howling Boo-birds.
C). I believe that this season was the fire-starter for the "Joe Montana" problem. Because of Joe's somewhat regular heroics, a large number of fans couldn't tolerate Devine putting him regularly on the bench. This had nothing to do with rumors of off-the-field troubles [I've never heard of some of that and consider it BS], but something most don't know, or if they were watching back then, didn't focus upon: Montana really stunk up the field a lot. He used to drive me so crazy in those days that I'd pray that Coach would start somebody else and bring Montana off the bench. Old Joe really seemed to shine THAT way, but who-the-heck-knows what his problems were when he started.
D). Coach Devine was, off the field, a "quiet gentleman" [Father Joyce's words] and a family man. My belief is that when he produced another strong season in 1980, he had proved what he felt he had to as far as his ND coaching abilities were concerned, said: I don't need this grief anymore, and retired to non-coaching positions at two locations where the people loved him [first Arizona State and then Missouri].
That's my take "from a distance". Maybe dshans knows better. OMM
p.s. He deserves the statue---we're Notre Dame; Coach Devine gave us a lot and wasn't well enough appreciated.