Already noted here by many - no HC, easy academics, good coaching, a little luck
to just say that it is coaching is way too simplistic. Article below shows 21 Boise State guys in or fighting for NFL jobs. That is insane in a state with almost no D1 talent, and isn't just coaching, it is also recruiting, academics or lack thereof, lack of honor code, an innovative offense, a banner win against Oklahoma, a quirky blue turf that gets attention, and being an ESPN darling. So coaching is just one of many factors.
http://www.idahostatesman.com/2014/07/31/3304408/twenty-former-boise-state-football.html
The thing that is amazing about BSU is how many DBs they have put into the NFL, 5 in the last 4 years I believe. Those aren't Idaho kids.....