Why would the Devils do this? If they really wanted Hanifin so bad they wouldve got him in the Toff deal.

Devils aren't spending big assets on a high end defenseman, and Haula blocks the trade

If Calgary wanted Haula and he was willing to go there he could have done so during free agency. Trading a player after signing them before a game is even played (barring sign and trade type things where the player is aware before signing) is a good way to get a very bad reputation with players. It isn't in the devils interest to do that.

The devils don't seem to be the ideal trade partner for a top pairing defenseman. I don't think they would give up that much for him and I think another team with less top end defenseman probably would give up more than they would.

HaloNO on the NJ trade, need more than a B to C prospect and a 40 point forward turning on the downside of his career.