His D-system is pretty unique, as is the D roster assembled to that template.
If he goes: some young D talent is devalued because it has more value in Williams' system than others (eg Barron, maybe TJ).
If he stays: I am not really a fan because:
1) I HATED his prevent defenses that lost the last 2 games.
2) I also HATE the soft corner defense that gives up 8 yard first downs sooooo regularly.
3) His defenses are too complicated. Some trickery in D is essential of course, but IMO he goes WAY too far. The tradeoff vs increased mistakes is not good IMO, especially if your D-roster emphasizes hitting vs intelligence (which seems to be how Snisher built it).
BC
