You're coming off as very disingenuous or desperate in your defense of the stats you prefer, at all costs.
Your hallowed xGF for the Caps in 2017-2018 was 27th in the league.
They were last in the league in HDF% (high danger chances for and against ratio).
Actual goals scored they were 6th.
Eventually, they finished First.
Hmmm
I've already gone over in detail what I think the predictive power of xGF% is. It's not 100% predictive, nowhere close. Having a good xGF% indicates that a team has some edge over the league in general, but that edge isn't huge. Goaltending is also another area that is hugely important, but also subject to huge amounts of luck. Same with shooting talent, where certain players are better shooters but again results are subject to wild swings in variance. Special teams too, where you can do everything reasonably in your control to score or prevent a goal but the puck just goes in your own net off a player's ass, or an otherwise perfect saucer pass hits a divot in the ice and renders the chance harmless, etc.
A team needs good luck to win the Stanley Cup, and the Capitals got that in 2018.
You're very good at asking questions but you've never answered: how would you characterize the role luck plays in the game in hockey?
I really do think this is the key reason why I disagree with you and others on the value of statistical analysis.