Some may not agree, but it's pretty clear the two remaining spots on the staff are reserved for defensive coaches, probably DL and DB.
DL because both Hoke and Mattison likely recognize the importance of a dedicated DL coach, and DB because, well, yeah. Two DB coaches is also a possibility.
So why no hires, especially at DB? Possible reasons:
 Mattison is too busy recruiting, and doesn't have time to focus on hiring coaches. He'll do it after signing day. Rushing it now won't help recruiting and if we've learned anything in the past three years, it's that chemistry among defensive coaches and coordinator matters.
 They have someone in mind, but he's still working... The best-known candidate in this category, Mike Trgovac (Packers' DL coach and Bo-schooled Michigan man), is not possible, since it would be a step backward for a guy thought to have a shot at the Denver Broncos' DC position. Joe Whitt, Jr. (Packers' cornerbacks) was coaching at Louisville (cornerbacks and recruiting coordinator) through the 2007 season, so maybe, if he's interested in returning to the college ranks and Woodson and Trgovac recommend. I don't see any possibilities on the Steelers, and the Jets guys are highly unlikely. As for the Bears -- Jon Hoke (defensive backs) is, yes, Brady Hoke's older brother. Surely there's been a thread on this?
Anyhow, what is the CW?