BCS coaching experience is not high on my list for position coaches or even a coordinator spot. In 2006, Arkansas hired Gus Malzhan out of Springdale High School to be their OC/WR coach; at the time Malzhan had no college coaching experience. Malzhan may be the best offensive strategist in college football.
In 2010, Tulsa hired Chad Morris to be their OC/QB coach out of Lake Travis High School. At the time, Morris had no college coaching experience. Morris is thought to be one of the best, if not the best, OC in college football.
In 2000, Mike Leach hired Art Briles out of Stephensville HS to be Texas Tech's RB's coach. At the time, Briles had no college coaching experience. Briles is one of the most innovative offensive coaches in college football.
In 1997, Kentucky hired Mike Leach as their OC. Leach revolutionized college football offenses. At time, Leach was the Valdosta State (Division 2) OC, Leach had never coached on the D-1 level.
To find the best coaches, it makes no sense to limit the pool of people considered. If there is a coach at lower level (even HS) that is doing exceptional things, it would be stupid to reject the candidate because you were not smart enough to bring him to the BCS level first.