The other thing that has greatly helped Gonzaga is the epic collapse of Pac 12 basketball over the past several years. Every now and then schools like Arizona or Oregon have jumped up and had great years but there hasn't been any consistently good depth in that conference for a while and Gonzaga has taken advantage to become the best basketball program in the Western half of the country.
I'd imagine it would be much harder for a non traditional program to do that in the middle of ACC or Big 12 country over an extended period of time.
The PAC in general has been a real mystery from an athletics performance standpoint in recent years.
In basketball you could always count on UCLA and Arizona to annually be in the elite tier of college basketball teams and several other programs were very good more often than they were average. The last several years, though, none of those programs have been worth a damn and UCLA feels like they'll never become a top basketball program again.
In football USC is one of the most storied programs in history and Oregon in the last couple decades stormed into elite program status. Cal, Stanford, Washington, Oregon State, the Arizona schools, Colorado, etc. have always been solid programs who generally compete in the top 25 with shallower droughts than in recent years. Yet the last several years have finished leaving us to wonder what in the actual darn has happened to football in the PAC.
Similarly, baseball seems to be trending down in the PAC. The baseball hasn't dropped off quite to the extent football and basketball have, but aside from a truly elite Oregon State baseball power the recent PAC baseball teams have been underwhelming. Arizona went on a run in Omaha a few years ago (we stayed in their team hotel the year the Chanticleers embarrassed the field with 78 mph fastballs), but I seem to remember them being a 3 seed in their regional and being the 2nd biggest surprise in Omaha that year behind Coastal Carolina. They hardly showed up as a juggernaut or carried any of the intimidation with them you saw from UCLA or USC or Arizona State in prior years.
Maybe what I'm noticing more is the deterioration of athletics at the California schools that's dragging the conference perception down, but after the last round of realignment, the PAC-12 Network launch, and the threat of OU and Texas defecting to form a PAC-16 I don't think anybody saw the decline coming that we've witnessed the last 3-4 years from that conference. Maybe it's an anomaly, but every year that goes by worse than the previous year it feels less and less so.