Yes you picked out all the stand outs, could you re-do that list with failed/not so great U-20 graduates from each club also?
I would also like to point out that not all of them took just their first season to stand out (Duffie, Fifita, McCullogh, Bromwich, Tamou werent stand outs in their first season) AND if you are going to talk about how good players are in the first season can you please remind how damn good Locke and Johnson were in the first year? How is Laumape going? Even Hurrell initially. That im afraid is GOOD graduation - that they can make an INSTANT impact in the debut season of first grade. It's a totally different problem if they can't maintain that form in the seasons after, not because our u-20/first grade graduation is shit.
A poor graduation would be taking a few years to develop after getting to senior grade and the only person who I can think who is like that was Ben Matulino. So go ahead and say our best player suffered from poor U-20 graduation
What players have really been put in the first grade and failed? Omar Slaimankhel is the only one I can think of. Maybe Glen Fisiahi to a point.