While both teams may be happy, are you really going to tell me that pre-trade, if there was a Hall for a D thread on this site...that everyone would have said Larrson was an even trade?
Anyone who knows what is needed to have a successful playoff run knew that EDM desperately needed at least one solid Defenseman. If Hall was the price, then so be it.
I would argue that the Leafs need EXACTLY the same thing. Reilly is good. I like Zaitsev, so far. Gardiner is good for offense. They need a legit Dman....one who can play D.
The days when an all offense team can win a Cup are long gone. You need at least a very good goalie, and a very good D( though that can be a team that plays great team D, rather than great Dmen).
I'm not saying that the Leafs should trade Nylander, unless they can do it for some Dman who is a no brainer. I think they should trade him for a Trouba, for instance, and for a Lindholm( who is having an uncharacteristically bad year so far, possibly making him available when he might not otherwise be). They would have to add in both cases, but Nylander can be the main piece. Otherwise, they might just have to wait, and hope that a draft choice develops into a really good Dman. No one is going to trade the aformentioned Dmen for bits and pieces, unless there is a weird situation like what happened with Trouba earlier this year, Hamonic the year before, and Johansen( though he netted back a very good young Dman).
It's hard to say how good Nylander is going to be, but it seems clear that he would be traded before Mathews( duh), and Marner, who is terrific.