Oregon is the most successful Pac-10/12 team since 2007. So it might just be meaningful that five of its nine assistant coaches have been in Eugene since the Ducks' golden decade began.
No FBS team can match that longevity, and it's even more notable that it's lasted through four head coaches, with loyalty flowing both ways through Rich Brooks, Mike Bellotti, Chip Kelly, and now Mark Helfrich.
Consider this list of "The longest-tenured assistants in college football," from CoachingSearch.com, which found that five of the 42 assistants entering at least their 10th year at a school are at Oregon.