IMO, defensive coaches rarely make good long-term head coaches in the modern college game, especially at Tier 3 programs. ***(Saban/Smart cheated and they are Tier 1)*** The reasons for this:
1. It's hard to win with defense at a school that can't recruit top talent.
2. Evaluating defensive personnel that fits the scheme, with high upside but raw skills is more important than the actual defensive schemes or gameday coaching. Some of this can be done with off-the-field hires. In other words, it's easier to find a defensive coordinator.
On the other hand, offensive coaching takes a more cerebral approach, where scheme and playcalling make a huge difference. One can also argue that offense requires more repetition and timing, so a stable influence is important. You can replace your defensive coach if he is hired away. It is much harder to replace the OC without missing a beat. Stoops (Tier 1) succeeded because he had such a huge offensive coaching tree created by Mike Leach
But if you want to stick to the defensive side of the ball, why hire a guy with very little coordinator experience like Nansen? Barry Odom is sitting out there right now. He's a much more proven commodity and he's got a good OC with him, even if it won't last for long. He has a network of coaches to fill out his staff.
This hire would make no sense, IMO. Players should not determine the head coach. They have no idea what they're doing. They are emotionally invested in their guy.
I'd trust the collective before I'd trust an administrator or a bunch of players, but none of them should be making this decision. It's beyond time for GMs at this level of ball.
I'd hire an offensive wizard with head coaching experience at the lower levels. Kalen DeBoer a few years ago is a perfect example.