Brink's play didn't "slip", it collapsed, xGF 35% his last fifteen games, that Deslaurier's territory!
Watching the AHL, it's a good place for someone like Brink to work on his game with no pressure, the difference between the AHL and NHL is less about speed (for example, players like Avon and Tuomaala have plus NHL speed) than skill, experience and IQ. So a young player making the transition from college or the CHL gets a taste of NHL physical play and smaller windows. Brink needs to get stronger and work on his skating and his off the puck play. I expect him to start next season, but right now the AHL is a better place for him. Lots of players spend a couple years going up and down before they win a starting job, it's not just a "Flyers" thing. He lost half a season of development last year due to injury and it shows.
MacEwen (22g), Brown (11g), Willman (12g), Lemieux (21g) are all getting NHL time this season, three with playoff teams. However, they make no sense for a rebuilding team except as placeholders.
Lycksell was tentative last year, maybe he was intimidated, but I think his real issue was he was a classic tweener, not good enough offensively for a top 9 role, not physical enough to play a two way game. Watching him so far, he looks stronger and more assertive, he's not skilled enough to get by with a finesse game, he needs to be able to play in dirty areas and do more than make pretty plays.