b/c there's maybe 5-6 goalies in the NHL that you can rely on consistently for year-to-year great numbers on average. & those respective teams who have them will probably never trade them (ie: NYR, WPG, NYI etc).
most teams are taking chances on no name guys (Binnington, Murray) or journeyman players (Kuemper, Hill). even w/ a HOF goalie, the Jets haven't accomplished much of note in the POs.
so what's really the right approach 
1. Never, ever use playoff results to measure team success.
2. Get a coach that plays a defensive system that adequately supports the goaltender.
3. Adjust whatever pieces you need to maintain said system / don't mess with a working system.
4. If available, look for goalies with a positive GSAx ratio over a longer time period.
That gets you most of the way to the promised land. That's pretty much what Boston has done - the team has been rock solid for a decade, and they've hardly ever suffered from bad goaltending. The transition from Rask to Ullmark (to Swayman) has been managed nicely, in part due to a team that has made their goalies' jobs much easier.
Another example would be the Isles in 2017-19: run-and-gun style of hockey got them some of the worst goaltending in the cap era in 2017-18, but when Trotz stepped in the year after, the team became one of the better defensive performers in the league. Thomas Greiss literally went from being a total non-option in net in 2017-18 to a top 5 goalie in the league in 18-19. That wasn't an accident.
Of course, not every goalie is going to thrive even in the best of systems. But if you increase the likelihood of that happening, you'll spend less time looking for new solutions. That's precisely what Edmonton and Toronto are struggling with now: their teams don't help their goalies, so bad goaltending ends up hurting them noticeably.
We are in a fortunate position with Hellebuyck. His career
low has been 0.153 goals allowed above expectation per 60 minutes, which is just stupidly good for a goalie playing in his ninth season. If your low point was your first year as a starter behind an atrocious defensive team, and it still wasn't even unplayable by any means, you're a true star.
Out of current star goalies, only Sorokin and Shesterkin have been better (both with four seasons played), and looking at retired goalies, the two most relevant comparables are probably the veeeery mediocre Tuukka Rask and Henrik Lundqvist. Helle could well be the best of his generation.
