I would be hard pressed to think of an FCS head coach that moved directly into a P5 job.
Usually FCS coaches get a crack at a G5 job, and if they do well in the G5, then move up to the P5.
I took "BCS" to mean P5. There are so many acronyms ... it can get confusing.
Here are the main ones to know:
Official NCAA "sub-divisions" of DI for college football:
FBS - bowls ... this was formerly called DI-A
FCS - playoff ... this was formerly called DI-AA
Media names to describe the "haves" and "have-nots" of the FBS:
P5 - power 5 (Big Ten, PAC12, Big 12, ACC, SEC, + Notre Dame)
G5 - group of 5 (Mountain West, MAC, CUSA, Sun Belt, American, + BYU and Army)
Post-season systems:
BCS - this is the old system, that had five bowl games at the end (championship was separate and would rotate among Rose, Fiesta, Sugar, and Orange). Used the AP poll, coaches poll, and a bunch of computer rankings.
CFP - this is the new system, which has six bowl games (the four mentioned above, plus the Cotton and Peach), two of which are considered the semi-finals of a four team bracket, an then there is a seventh game that is the two winners, which is played after the bowl games in some bid out NFL stadium. Uses a committee to form its own ranking.