Any and all of those could improve by hiring ND guys.
In some ways I look at it as an organization hiring a development director. Say the organization is a Catholic high school. Candidate A has extensive knowledge and 20 years experience in the development field and has had success building relationships and raising money. And then there is Candidate B. He too has the same experience and knowledge as A. But Candidate A was a product of public schools and is agnostic. Candidate B is a product of Catholic schools, is a practicing Catholic, and an alumnus of the high school. While Candidate A could be a great choice, Candidate B would presumably be the no-brainer hire. He'd bring an enthusiasm Candidate A probably couldn't provide and a genuine message Candidate A couldn't provide. So you have a guy out there selling the school who truly buys into the school. That veracity and enthusiasm has a way of seeping out to other departments, to faculty, and to students. The pride and mission factor of "our school" raises even more.
Does it work out 100% of the time? No. But there's a reason Bear Bryant left for Alabama, Jim Harbaugh left for Michigan, Urban Meyer went back to his home state, and people everyday, in all walks of life, go back "home."
I think Brian Kelly has the "coaching" part down, I think he needs more of the "ND" though.