Soup to the flames?

why trade him? he is a useful player

Haula is reportedly already working out a long term deal with NSH.

Something tells me, TOR is about to have one of Petty or most likely Matheson from the penguins.

Something like this.
Hallander -> PIT.
McCann to TOR,
Seattle selects Matheson from PIT.
Seattle selects McCann from TOR.
Matheson -> TOR
TOR pick -> Seattle.

Something in those regards.
Rough base of what this is going to look like.

What each team gets.
Penguins, Cap space and a solid prospect. Draft protection for other guys.
TOR, cheap capable defenseman. Draft protection
Seattle, McCann, what ever they get from TOR for Matheson.... possibly something goes back to the penguins.

Gee, teams that need speed and muscle....Leafs keep Mikheyev at 1.6m, and don't resign Foligno.

Interesting and crafty suggestions.

But why would Toronto give up a Forward they could really need in terms of LW, PPG (led PIT), zone entries, killer instinct (such beautiful hard efford goals last season) to add another D-Man?
Dermott´s new contract already is too heavy and will cost against the cap if they'll sent him to the minors.

It was never about you, and getting McCann was never about him being i leaf. It's simply holding to finish the deal.
McCann is the price PIT pays to move Matheson. He was always meant for Seattle.
TOR gets protection in holding him, they probably give something up then for the defenseman Seattle takes from PIT.
A guy like Matheson, who can skate and drives offense, helps TOR. Who will lose Reilly. They get him with term cost controlled.
In return TOR gives something back to Seattle for that.