I know the options on hand are underwhelming for what we would like, but looking at their head coaching records isn't necessarily an indicator of what they might be able to do. We wouldn't be asking any of them to be head coaches, just competent coordinators or even position coaches. Can they be that? Maybe or maybe not, but I know that what we have in those positions now sucks and there's at least a chance of improving with a change. Particularly at DC. Maybe a new DC could get the existing position coaches to actually do some decent coaching too.
A good head coach isn't going to be afraid to make a move midseason if things aren't working. Riley changed DCs midseason last year despite having only one loss because he knew change was needed, and still made the playoffs. He didn't keep Stoops out of fear of making a midseason change, even though you could argue McNeal wasn't a sure success either. There are other examples out there of guys that had the balls to make a move because what they were doing wasn't working.