From a practical, day-to-day perspective, the biggest loss by far is Venables. They had a down year by their standards, but they would have had a horrendous year (maybe as many as 4 more losses) if it wasn't for their defense.
I don't think Elliott is much of an OC tactically (that was all Watson/Lawrence/their WRs/Etienne), but if he's a good recruiter then it is a loss. Losing the AD is kind of jarring because he's he leader of the athletic department, but he didn't hire Dabo and honestly I don't think has had to make a bunch of consequential decisions there in terms of personnel. I think he's made a few hires in the non-revenue sports, and he's let a men's basketball coach who isn't very good and was hired before he took the job stay on.
Dabo needs another electric QB is ultimately what it boils down to.