My best guess is that there is far less competition for talent in Idaho. Seriously, Boise St is like Ohio State in Idaho, all of the kids want to go there. So in a conference like the Mountain West they seem to perennially have better homegrown talent than anybody else. Long story short unless they join a power 5 conference I don't see them losing a great deal with or without a great coach. You don't seem to get how hard it is to maintain a 75% win percentage after that many years. Give respect where it is due.