Bill Clark at UAB is a good coach. There might be, at most, 6 coaches in the last 50 years who didn't play CFB. On the other side there are hundreds of coaches with CFB experience that weren't successful. So CFB experience isnt really a good metric. There are lots of coaches with college experience that use gimmicks too.
I'd be concerned if a coach didn't play at any level, but plenty of HS's had harder practices than some colleges. For example, my HS was a state powerhouse in football. Then went to a D3 college and probably could have been on the roster as a 7th stringer. Didnt have interest. From friends on the team I heard practice wasn't any harder than HS (actually might have been easier since HS football coach had basically no rules or oversight).
This may surprise you but given the small sample size, it is statistically MORE likely that a HC will play in a BCS game if he didn't play college football than if he did.