Oregon poaching Leach's best assistants on a yearly basis (not to mention other departures like Manning going to UCLA) really drove home for me that long-term major success at WSU is nearly impossible absent more institutional support (i.e., more debt and/or money, and as we know, more debt isn't going to happen anytime soon). Not just "hard," in the same way it's hard for any program and almost unheard of for non-blue bloods absent major changes in circumstance (e.g., Oregon/Okie State), but just about impossible. I believe that to the extent Leach didn't already know that, it cemented it for him, too, and that is one of the things that led him to look around and bail (even if one grants that him being open to bail also contributed to further losses of assistants or, while I disagree that he was, any degree of being "checked out" that people have claimed).
Even with a coach capable of building up to a team #2 in the country in a disadvantaged spot, and on a materially similar track here, having assembled a staff that was pretty great by WSU standards--the one Leach had a few years in with Grinch, Salavea, Wilson, Manning, Sage, Mastro, etc.--it all could be derailed easily by a program with more money and otherwise preferable circumstances (easier recruiting, higher profile, better facilities, etc.) luring away assistants. No coach in America, and certainly not any that WSU reasonably could hope to hire or keep around long-term, could overcome that by consistently executing perfect hires every winter from a pool of Mountain West graduates and retreads / unusual situations and overcoming any discontinuity on the recruiting trail, especially with WSU's structural limitations on that front.