Kent, you make some good points. You mentioned Tiller, and rightfully so. I think the comparison to Tiller (and his very quick success), whether it's recognized or not, is what's really fueling some of the Brohm-hate we've seen.
Most people significantly underestimate the "perfect storm" Tiller walked into. He had multiple future NFL OL (Matt Light was moved from TE to OL), a seasoned QB (Dicken) who could learn quickly and make good decisions, very good skill players, the solid nucleus of a reasonably good D, and an offense that the rest of the league simply wasn't prepared for. Throw in the recruitment of a future NFL legend/HOF QB very few programs wanted to take a chance on, and that gave Tiller, Spack, et al the luxury of moving players around (I believe Jason Loerzel was moved from TE to LB?).
Although Colletto was not a great recruiter, I think we all took for granted exactly how much talent was on that roster in 1997.