Most important is DC. We have an OC already - they don't have to make a move if they don't want to. Given last year's O they might want to.The two most important hires left are offensive coordinator and defensive coordinator. Depending on who those two people are, it will decide just how fast this team can turn around as soon as next season, obviously depending on the draft, and finding a serviceable, free agent quarterback.
Supposedly Jerod and Steve worked well together and the defense ran well with Steve apparently making the calls. How that works itself out would be very interesting. Given last year's D they might want to keep the same D coaching staff. A change here could work or ruin the D chemistry that has been building over the years.