According to Wheeler, Helenius had a disappointing WJC, even though he's more advanced than Jett.
Jett really wasn't going to show much offensively, both b/c of his wings (basically muckers) and because of his usage, PK, 4th line, playing with a lead (expected to play it safe). The Flyers have no control, but hopefully he'll get traded in the next couple weeks to a more talented and offensively oriented team. If he stays on Guelph, I can see the Flyers keeping him next year b/c he can probably develop faster in a sheltered role than on that team.