Hellebuyck is a world-class goalie, this doesn't change that. What it does show, however, is that the playoffs are always a crap shoot. An average goalie can get hot in a small sample size, and an elite goalie can poop the bed just as easily.
You always want to go in with the best goalie in the series, but if you leave him out to dry more often than not and just can't match the opponent's skating and level of chances, then it will likely not make a difference.
This just continues to prove there is no sure thing in net these days. The team style of play and structure makes a bigger difference these days in my eyes. The speed of the game is just on another level compared to when there were more than just 2 or 3 goalies you could consider elite.