Paidagogos,
Marsden wrote several good books on fundamentalism from an outsider's perspective. His Reforming Fundamentalism is an excellent history of the beginning of New Evangelicalism and the decline at Fuller. He does not agree with Fundamentalism and so paints it in a particular light, but his knowledge is wide and deep. I would study church history under him in a heartbeat because he knows it, perhaps as well as any current scholar. When you want to be "good" in a particular field, you try to study under the best available mentor. Marsden fit that category, and I am fairly sure that is why IV went there. If Olasky said that (and I don't doubt you; I just haven't seen it), then I think he is right. I think IV is a conservative evangelical who doesn't see eye to eye with III and Stephen and the university. BTW, I don't think IV ever finished his work at ND.
IV was never going to fit in at BJU although I think there was an effort made in the mid-90s. It was always Stephen that was going to fill that role.
As for ND in the 70s, I think several things. First, ND was probably more catholic then than they are now. Second, I have no idea what Falwell's son went there for. Third, Jr. was a much rougher cat than III is, and probably would have been publicly stronger. Fourth, they may have just been inconsistent.
III is the kindler, gentler Jones, whether for better or worse, richer or poorer ... well, you know the drill. Another well known perspective was that when Miss Barker and Jr. were off the scene, there would be a softer, gentler BJU. They were really the last remaining icons of the "old guard" so to speak. There have been many changes made to be sure. In deference to BJU, I don't think they look at those changes as theological in nature (again, whether right or wrong). They do not believe they have never compromised their theological convictions; they have changed the application of some of them though.
I wonder if some of this isn't that there was a failure to clearly delineate between doctrine and application. Foxrev talked of those who blindly follow BJU today. But I can't help but think he is one who is blindly following the BJU of yesterday. He eagerly soaked up the teaching and application of that era and thinks that it is the only right way. But, as with areas that have been shown here, there were clearly some applications involved, not doctrine. He held BJJr in a high regard (as many did, and rightly so). But you still have to make a distinction between doctrine and application. The one is infallible; the other is not. BJJr was well known for shooting from the hip when he talked to the "preacher boys." And when you shoot from the hip, your aim is quite often off target. And quite often, he was probably giving his opinion about matters, rather than saying everyone had to agree with him to be saved.
I think preaching from all sides (from rabid KJVO to radical liberalism) is infected with this failure of clear delineation between doctrine and application and it is something that we preachers and teachers have to be very conscious of.
But I have gone on long enough. Hope that is clear ...