One of the big challenges that non-blue blood schools have is retaining good coaches. Utah experienced this very thing with Urban. And plenty of coaches at blue bloods used to coach at smaller Power schools. BYU doesn't quite have that problem because our coaching pool is limited to mostly guys with strong BYU connections, but the downside is a much smaller pool.
Anyway, what I'm getting at is that if Scalley turns out to be a great HC, you know he isn't going to jump ship if a bigger school comes calling. A different coach very well may leave after a good season or two, and all it takes is one bad hire for things to fall apart (see Arizona). Continually replacing HCs makes it hard to sustain success. Scalley brings continuity, but you could also give him a short leash, say two seasons, because of it (no need to get his guys into the system, they're already there). If Scalley doesn't work out then you can look elsewhere.