There have been plenty of flukey cinderella runs in the playoffs, mostly on the back of PDO binges.
In the last 10 years or so alone we've seen:
Ottawa in 2017
Phoenix in 2012
Montreal in 2010
You could even make arguments for Dallas in 2020 and Vegas in 2018, as both significantly over-performed on the basis of unsustainable goaltending and shooting percentage before house of cards fell.
Before that you had the likes of Washington going to the Final in 1998, and many many more before that.
It's kind of hilarious to suggest Bergevin is a genius for taking a team that finished 24th in the league, turned it into a team that finished 18th in the league, fired the coach midway through the season cause the team was struggling so bad, the team only makes the playoffs cause Calgary is somehow even worse and Vancouver gets the plague, and then each round of the playoffs their opponent loses a top 6 center. That's some 5D chess right there if you want to pretend this path was the plan all along.
Forgot LA's 2012 Cinderella run.