college and pro (NFL/CFL) all coached in HS, for nothing. guys like Malzahn who were established coaches in HS rarely move on. it's the vagabond who coaches some in HS, then is a grad asst or position coach, then on to other things. the career track of a coach is strange. look at john harbaugh. the guy had no resume' indicating he should have been a HS, but he got an NFL job.
i'll give an example of my buddy. he graduates, goes on to coach at his HS as an assistant. gets the HC job a year or two years later. after two years, he goes to a D1 school where he was a position coach for a year. applies for a CFL job and gets it. has the best position group in the league, but the HC gets fired and he's out of a job. goes back to the HS for a year, then back to D1. now he's in the NFL.