The Flyers under Briere (and give Fletcher credit for rebuilding the development side, from facilities to personnel, Briere has built up on that, Fletcher was a better administrator than hockey man).have a good track record developing players.
One thing I've noticed the last couple years is players promoted from LHV don't look out of place, many were marginal talents, but they've been well coached.
Players like Foerser, Brink and Cates improved their skating.
Bump made a big jump from last year's AHL POs (right out of college) to this season.
In hockey teams don't control players the first few years after drafting them, the Flyers stay in contact, bring them in the summer, but NCAA rules limit them as does the CHL season. One reason they're willing to gamble on Sokolovskii is he's with London, which is almost a pro team with Dale Hunter running the show - look how fast Barkey was able to make the jump to the NHL.College is better for development b/c they have more time to train and practice with half the games of the CHL, but young players don't get much PT which is why you see them stay in the CHL or USHL until they're 19 or 20 so they can play a lot of minutes against suitable competition (imagine baseball players starting in low A then going to college).
I'm withholding judgment on Jett, he'll get a chance to play in LHV this season, with intensive pro coaching and not jump around to 4-5 teams in a season. By spring we'll have a much better read on him.