Bill belichick never coached anywhere but the pros. he started out I believe with the baltimore colts. And I'm pretty sure he got that job because of his father's connections.
Listen I get it. I get as irritated as other people when people get jobs because of who they know or who they're related to(to me,that's the same thing). I think that's happened to everybody in every profession. but if the person turns out to be competent, then it's fine. the problem with it is if the person sucks ass at the job and you need to fire him or get rid of him. does that ever happen? probably not often enough
*edit*@Dingleberry said it better!
Doesn't he always?