I also see Petan as a bit of a cautionary tale for us. The top prospects that get to this point have learned to be resilient and work to achieve their goals. If management guesses wrong on if they are ready and they turn out not to be, for the most part no damage done. If anything players can then take what they have learned apply it at a lower level and then jump up when given another opportunity. In Petan's case IMO it is playing with more speed in his game. Having so much offensive talent in junior he was able to slow things down and make plays. In the NHL you just don't have the time and space and he got caught a little flat footed out of the gate. I'll add in my bias around development and that is you need to expose your top prospects early to the NHL since those are the players they need to succeed against. If you hold them back a year or 2 they will still need to learn all the same lessons at the NHL level when they get their opportunity.
