I don’t think there’s much use in trying to assign blame to this or that player or whatever, when this is an issue that transcends who’s on the field. The roster has changed a lot over the past six years, but no matter who is out there, one constant remains: they aren’t ready to play.
This is 100% a coach/staff issue, and about the only thing I can say for sure right now is that the problem clearly wasn’t Callahan.