This is a common problem around here. Potential isn't a guarantee, it's an estimate. You're no more likely to reach it if you spend your whole teen years in JR than you are if you make the team. A prospect isn't "ruined" because they don't reach their potential. If every player reached their potential each team would have 4 #1 C's and 6 #1 D's, but it doesn't work like that. Their potential should be seen as a ceiling, not a floor.
How is this factual evidence? How is their factual evidence that playing someone too early ruined their future either? Kris Russel certainly looked good in JR, how come he never turned out to be good in the NHL? There are countless players who's career could, hypothetically, could have been ruined from being sent back. There comes a point in the "blue chip" prospect stage where they can't learn anything at the JR level; And having seen more than half of Riellys games last season, I can say that's the case for him.
Prove to me that a career has been ruined by calling someone up too early. And at the same time, prove to me and extra year in JR never ruined a kid. You can't.
Good topic. I've had this conversation with a few leaf fans when discussing Morgan Riellys 2013-14 season. We could never think of anyone off the top of our heads but we can all think of hundreds of kids who were rushed.