They only played nine games so far, too few by far to judge a player/trade.
Also even if trading Hall for Larsson improved the team - which it might have, I don't know the team well enough so I defer to experts - the point is that Hall is so good that they could almost certainly have gotten someone much better in return. (After the trade some journalists said other GMs told them directly that they would have offered more/better.) Larsson might be good for them, but I still think it was far from ideal asset management. It would be different if they had traded, say, Eberle, but Hall is an elite player and Larsson "only" very(?) good.