For the 2017 expansion, any existing NHL team could protect either one goalie, seven forwards and three defensemen or one goalie and eight skaters of any position. Additionally, two forwards and one defenseman per team who have played a minimum of forty games in the previous season were exposed. Meaning an integral three skaters became available for poaching. The best #2 goalie in the NHL was Fleury, who is a freakishly outstanding goalie (with a history of injuries). Fleury was key to the Penguins Cup win last year. He is on track top be instrumental to a Cup again this year.
No other league (and previous to 2017 neither did the NHL) allows a team to basically build a team from all top 10% players. Sure, they didn't get the top 1-5%, but if they weren't getting the cream, they were still getting half-and-half.
After that, the team has been well managed from ownership down to coaching. Astute changes have been made through the season, which is easier to do when the fan base isn't invested in any single player.