I'm not Lori, Tim, or John, but I figure I'd put my 2 cents in.
IMO, I think it's all about continuity. Ralph is getting fed up with constantly changing coaches/systems over the past 12 years, and starting over again, and again, and again, and rebuilding over, and over, and over again. He must feel that we are close, and that if we just stick with the system for long enough, we'll finally make that push into the playoffs and beyond.
Hiring a proven HC and staff will require that the system, and the players, most likely, will all need to be changed and overhauled as well, and Ralph doesn't want to see that happen again.
Again, no facts here, but just my opinion.