Let me start by saying I would not trade Ghost for Hall.
People are right, Hall is not the type that plays a 200 foot game. In junior he played better defense, but also back then it wasn't his job. In the NHL, it's everyone's job. I'd like to think he can develop that skill and be better in his own zone, but if not, what you see is what you get.
It was similar for Semin. People raved of his offensive skill, he signed a big deal, and the fans hated him because he didn't play defense. Well news for everyone, he never played defense.
I feel Hall is similar, if you're going to get pissed about his defense, then why trade for him, or sign him to begin with? In Hall's case, I feel like he will develop that with more urgency on a team that is perennial bottom feeders. It may speak to his professionalism, but I feel like if i played for a team in the bottom 4-5 for my entire career to date, i'd wonder why i'm playing hard at all.
Also, you don't trade players in a position of prospect strength because they may not achieve their value here if you don't. Last I checked, the Flyers are in the business of winning a championship, not supplying other teams of highly coveted pieces because the flyers wont "maximize their value as a player".
Thats a ridiculous argument in my opinion.
Let the kids develop, and in a couple years we'll be back to discussing the goaltending....