Since 1996, BYU hasn't done anything really all that great. 2001 you can kind of point to, but even that went up in flames to end the season. 2006 was a good year... but still turned into a coulda shoulda... the only reason that 2007 is pointed to is because the expectations were low that season, but when the expectations were raised for 2008 as a result of 2007... they aren't met and Utah goes on to their second BCS game. Then 2009... again more coulda shoulda.
Nothing BYU has done in the last 18 years has even came remotely close to what BYU accomplished in 1996. So right now, you have a bunch of 18 year old fans that are living off the stories of BYU's great teams and haven't seen them, mean while Utah has had 2 undefeated seasons, a Fiesta Bowl win and a Sugar Bowl in over Alabama... and are now PAC12...
BYU has made more bandwagon fans as a result of trying to do the same thing over and over again and expect different results... and living off the past.