I've been on the side of keeping Coach Rose a while longer due to his sustained success and uncertainty regarding a potential new hire. However, a study of leadership that I just saw (granted, it's old) showed a curvilinear relationship between basketball coaches and their success. Basically, coaches improve over time for a while, and eventually performance begins to decline. The magic number: 13 years. Maybe another year is warranted, but without evidence of turning things around, it really may be time, even though I really like Coach Rose and all he has done for BYU.

Eitzen, D. S., & Yetman, N. R. (1972). Managerial change, longevity, and organizational effectiveness. Administrative Science Quarterly, 17(1).