I wouldn't put too much stock on these WJC games. Canada in overall is in trouble. There is not structure and lines are shuffling so fast that there is no chemistry either. Canada plays mostly along the boards and without proper rhythm so quality of the passes is bad and in most cases the play stops to the blue line. So Marner can't even use his speed or skill. You need either proper breakout pass or you'd need to play puck though the middle in neutral zone.
Mostly zone entries come also along the boards or dump in's so if Marner don't have the puck he'll get it in the corner or he has to fall back to blue line and there he usually has no speed. Marner tries to circle around the offensive zone, but he can't get the puck from there. So he goes to blue line or behind the net and in worst cases he wrestles with one big dman.
If you want something out of speedy and shifty forward you need to get him the puck and get the line mates near, so he can pass or force himself on 1on1. No Marnes has little or no speed when he gets the puck and play is stagnated.
This same goes for Strome and he suffers too, but his bigger so when his playing along the boards at least he got the size. Same goes for Virtanen and Crouse. They can cycle the puck better, because of the size, but you can't do much if play starts from the corner every time.
When play broken up in the neutral zone and puck carrier has speed and line mates near him your game looks really good. Enough skill and speed. Or if defense can play the puck to center or forward in the middle that can pass it forward, then it works.
Now you chip the puck to the boards and if there is no speed winger chips the puck to deep and then other forward forecheck and try to wrestle the puck out of the corner. Those bad saucers are one problem because you can't really play the puck fast to anyone.
That is not the environment where small skilled wingers succeed. Either you have to get better breakout passes or at least some structure.
I'd blame the coach, because PP is same stagnated gong show with slow and bad passes. There is no tempo or idea.