I think 3 years is appropriate time frame for very prestigious programs like Michigan and ND to lose that 6*, Boise and TCU should not be 5* programs IMO. EA is way too generous in handing out these ratings, as well have made it too easy to gain prestige. Prestige shouldn't be a "What've you done lately" thing. It should go far back. I know TCU was quite a power in the 30's and 50's still not 5* worthy based on their mediocrity after that and Boise has only been FBS/D-1A since 2001 and only really known nationally since the 2006/07 Fiesta Bowl, they shouldn't be within reach of 5*'s. It should take minimum 2 years of success to go up a prestige star.
TCU 4*
Boise State Upper 3*/Bottom 4*