They were in year 2. They are now in year 5. The only big loss was the Boston series. No one expected us to take down the Capitals.The team added an entirely new core which had next to nothing to do with Lou. You could throw me in there as GM and we'd have that kind of progression.
The team was very mentally weak. They lost key games and made the same mistakes with greater frequency but Lou had the guise of "the core is still growing and learning" on his side. Plus we were coming off of a decade of mediocrity or downright awfulness, so the standards were much lower. There is no guarantee that things would have progressed any further under him... You are just assuming that would be the case. Other than seeing the natural progression of Matthews/Marner/Nylander and other prospects (and adding a very mentally weak Andersen), he did practically nothing to improve our team. Then he saddled us with contracts that needed to be dumped once our stars were no longer on ELC's.
I won't discuss Dubas because this argument doesn't really need to involve him at all. Lou can suck independently of any suckage that surrounds Dubas. That being said, I think this article explains exactly why Lou's management style does not work anymore and should not be heralded as a "solid top down organizational structure".
Council Post: Why Authoritarian Leadership Simply Doesn't Work Anymore
Why are the Isles more successful than us despite losing Tavares? Lou has a very proven track record of success that follows him. I believe its due to organization building and having accountability from the top/down. Who are the two most successful managers in Sports over the past decade? Nick Saban and Bill Belichik who both run very authoritative organizations.
Andersen was the easy scapegoat (he didn't really deserve it for the Columbus loss), but we started Campbell this year and couldn't score until we pulled the goalie down 3-0 in game 7 after getting shut out in game 5. Both of these loses are way worse than anything that happened in the Lou era relative to expectation. There's no guarantee he would have done better. But, I would say what we have accomplished in the last 3 years is so far below expectations it's hard to think he would have done worse.
Lou was hard on players, but was fair. He commanded respect, which carries through the organizations he works for.