Calder race is quite important to me, and while my pick is obvious, I truly believe in him.
Bit of history, Flyers have never had a Calder winner (or Art Ross for that matter), and have only have had 3 nominees. The last was in 1994 (Renberg). We've always been a win win win team, and have never really put ourselves in a position to have too many great young players for calder consideration.
Ghost came into the Flyers lineup and had an immediate impact. His first 15 or so goals all either tied a game or put the Flyers ahead a goal. He was an overtime wizard. He set pretty much every Flyers rookie defense record, and many league records. And here is the icing on the cake, he did if after seeing last season cut short by a very serious injury. He missed basically all of last season, got himself into game shape, got called up early and looked like he never missed a beat. And my favorite part about him is that for all his flair and offensive upside, he showed a GREAT defensive game, especially for a rookie. There were 2-3 games all season where there were some obvious rookie flops, but this kid gets back quick and makes a big difference.
All that said, as others have mentioned, it's a stacked year, and there isn't really a bad choice.