VOORHEES, N.J. – Concussion complications have threatened a number of hockey careers but usually that trauma surfaces somewhere well into the timeline. For the Flyers’ Alex Ciernik, the danger arrived before his possible stay in the NHL even started. Ciernik, a fourth-round pick in last year’s draft, suffered not one but two significant head injuries last season and his recovery time limited the forward to just 26 games in the Allsvenska Hockey League. [...]