Jim Harbaugh is a bad example. He played in the NFL from 1987-2000 and became an assistant coach with the Oakland Raiders for two years in the 2002 and 2003 seasons before becoming head coach at the University of San Diego. Not to mention his brother has been in the NFL for years.
BK has no connection to the NFL in anyway and that was hinted as much by a sports reporter whose name escapes me. BK would be a terrible hire for the Eagles for that very reason.
Saban lasted two seasons with the Dolphins and reports had it that he didn't even want to go to the NFL. Regardless, he also was a DC in the NFL too.
Pete Carroll had a lot of previous NFL experience.
Even Greg Schiano spent a few years in the NFL.
Bills recently hired Doug Marrone...has previous NFL coaching experience.
My point is that the NFL does not hire a guy with zero ties to the NFL to be a head coach, especially a team like the Eagles who need a good hire like Lovie Smith. All these guys have some connection to the NFL in some coaching capacity. BK has none.
The NFL is going through an evolution. Pro teams are having success with spread/read option/dual threat QBs. Because of this, NFL teams are tapping into the FBS-well where coaches have experience running these formations/offenses. Because the NFL traditionally doesn't hire college coaches without NFL ties, doesn't mean there's no precedent for it.
't the NFL, it isn't a joke either.