I understand it's not the be all and all but I don't think conversely a good performance at the WJC should be entirely discredited, nor should a bad one. I don't think it definitively says whether a player will be good or bad. The Pettersson example is a good one but I think Gibson is a good example to the converse. It wasn't that long ago that Gibson had a rough first playoff appearance and people immediately wrote him off. People actually with no irony or joke said that he would plateau as an average starter in the NHL. And I'd point to his junior career and WJC dominance and people told me it didn't matter. Well here we are now and Gibson has cemented himself as one of the elite goaltenders in the league and his lights out performance at the WJC mirrors the quality of play he puts out now.You can't base future success off the WJC.
There were people that watched Pettersson's WJC performance and wrote him off despite his domination of the SHL. Lunacy.
I don't disagree with anyone who says it's not a definitive stamp on what kind of career a player will have. For example just today someone said that Evan Bouchard will cap out as a bottom pairing defenseman in the NHL. And that may well be true but it's too early to say that. However his run of spotty defense certainly indicates that he's got some work to do. The WJC may not be outcome determinative but it's certainly not a useless window either. I may have been hard on Owen Tippett through the group stage but I certainly don't think that means he's a bust, just that he needs to work on being aware of when a pass is coming and getting his stick on a one time shot properly. Since his tendency seems to go for the one timer. Or he could try something different and settle the puck first and try to take a better shot or look for another pass. Certainly what's been happening in these games of getting fed with passes along the left wing and misfiring over and over again cannot be something he leaves unammended.