Last year was a turnoff because BYU underperformed. Yes, the defense wasn't great, but BYU has had a ton of mediocre defenses, but great offenses kept games close and exciting.
Most BYU fans aren't unrealistic. BYU has been able to field NFL quarterbacks and occasional NFL skill players for the last 40 years. So it isn't unreasonable to expect that BYU should be able to continue to do so. It is probably unrealistic to expect BYU to have similar talent in the secondary, but expecting BYU to have a great offense is not unreasonable. BYU should be able to have a really good QB, a strong, quality O-line, intelligent and quick route-runners, and a dominant tight end. BYU should have a top 25 offense.