One of the many storylines that has developed regarding the David Jiricek-Bobby Brink trade is that when the Flyers drafted Porter Martone, there were too many players at right wing. Someone was expendable, and it happened to be Brink. Brink was talented enough to bring a (hopefully) talented return.
However, things don't happen in a vacuum. Causes have effects, and effects tend to ripple out. While Jiricek is in the AHL right now, he'll most likely be donning the orange and black fairly soon. This means someone on defense is now expendable and will have to go.