from 2002 through 2004 we went 5-7, 4-8 (hit bottom) and then improved to 5-6 in 2004 barely missing going 6-5 despite playing the 11th toughest SOS that year.
The next year (Bronco's first) we won one more game despite playing one of the easiest schedules that year (72nd according to Sagarin) and that was with Bronco inheriting returning, experienced talent with a boatload of future NFL players (Kehl, Beck, Tonga, Coats, Collie, Watkins, Tahi, etc) and BYU all time greats (like Harline, Curtis Brown, Jake Kuresa, etc).
on the field we bottomed out in 2003 and the trend was on the up and up when Bronco took over in 2005, it's an easy argument to make that the turnaround was already in effect.