Al Davis could have had his pick of many coaches to take over as the silver-and-black's on-the-field leader, but he chose John Madden in part because of what Madden said during the interview process.
This was an unexpected turn of events not only because Madden was not a name on the NFL radar but also because he had not served as a head coach at the professional level.
That certainly would seem to be a factor that would be hard to overcome, but according to his book, "Hey, Wait A Minute (I Wrote A Book!)", Madden handled it by telling Davis, "I don't have any head-coaching experience in the NFL, but if I don't get this job, I'm not going to have any head-coaching experience three years from now or five years from now."
Madden was obviously a success story despite having a seemingly limited background, but the lack-of-job-experience quandary that he ran into is one that coaches still run into today.
For all the question marks surrounding Muschamp, the most common seems to be whether someone with no previous head-coaching experience can succeed.