I don't think you can argue "15 years" compared to anything other than other expansion franchises; until things are in place with scouting and development, etc., it's really hard to judge what anyone - coach, gm, whoever - has done.
If you look at the last 10 years, we got better, built a team, made the POs a couple times, then dismantled it. Rebuilt it, made the POs, won a couple first-rounds, then it imploded. Not sure you can hang the dismantling on Trotz or Poile.
So, I think it's disingenuous to say they haven't shown they can build a franchise, get improvement, etc. That said, I think you can hold them both accountable for the implosion after the mess in Phoenix. Poile made the decision on the "rentals", Trotz decided how to handle the curfew violations. Poile decided on subsequent contracts, how to handle the Suter-situation prior; Trotz had the room following.
While I understand why and how the Suter thing spun out on him, it's still Poile's responsibility. Handling Weber - same thing; even if it's all good between Shea and the club, the PR is Poile's responsibility, too; gotta' control the spin. We know that last offseason Poile's choices have backfired except Nystrom; while he's done some decent damage control on it, doesn't change how bad it is. Clearly learned from Hammer and Sutes - got something for Leggy, although given we were pretty much a lock not to make the POs makes it easier.
Trotz - I feel better toward him. I wouldn't have held those guys out of the 2nd Phoenix game and his line-shuffling can be frustrating, but I think he's done a remarkable job over the years molding the talent given to him into competitive teams. Would I like to have seen this Smith sooner? Yep - but I'm not sure it took so long just cause Trotz insisted he be responsible. Would I have like Willy in the middle sooner? Sure, but Poile signed guys that were Cs, not Wings, so Willy on wing made sense most of the time, regardless of what "system" the coach wanted to employ.
In the end, if I'm making a change, it's Poile. Not sure I feel it's because he "deserves" it, but because someone is accountable following the implosion, and I think over the last couple years - while he's certainly made some nice gets for Erat and Leggy, and there really wasn't a thing he could do about getting Seth instead of an F - I think he's the guy who's "results" are less than reasonably expected, not necessarily Trotz'.