The 2007 OU-Boise State game drew an 8.4 rating, and that was good for the eighth-worst rating for a BCS bowl game going into last year (tenth-worst now). So while Boise State-TCU drew an 8.2 rating and was fifth-highest rating of Fox's BCS coverage, it still ranks pretty damn low against all BCS bowls. Last year's Boise State-TCU game is good for ninth-worst ratings in BCS games since 2003.
None of those Boise games were N.C. games anyway. Let's say Boise or TCU makes the title game this year. You have "David vs. Goliath" storyline for the national title plus ESPN hype train (remember the last two Boise BCS games were on FOX and this year's title game is on ESPN) plus the countless conversations on every radio show of "No way can Boise beat Oregon" and you potentially will have great ratings to keep the suits happy.
Don't underestimate the ESPN stigma for any title game now that they own the rights to all BCS games and their sole purpose it to push that product in our faces for 2 months.