Just because it's possible doesn't make it a good idea. I mean, you can jump out of a plane without a parachute, and not die. It's been done before (like over a forest or in deep snow). Doesn't make it a good idea.
Leftwich is a bad example. He's got Brady and Brady's all star vet squad. I could probably coach that offense and at least get to the playoffs. Everyone thought Bellichick was some offensive genius until Brady left.
What's so bad about a proven OC? Jedd Fisch was good. Whipple has had his good moments. Lashlee isn't a bad OC, per se, he just needs a dramatic overhaul of his run philosophy, especially in short yardage situations.
Nothing against Ken. Love the guy. One of my all time favorite Canes. Great QB coach, for even longer than 7 years (even when he was technically still a player, he was getting contracts to work with young QBs, such as Brady Quinn). I would just prefer it if we got someone who's already cut their teeth. We've getting dict around for 20 years. We deserve better.
GO CANES!!!