Treliving probably knows what every GM wants for every player in the league.
Apparently he harasses them all day long. With his stupid fantasy trade proposals. He wants to be in on all the action.
He's a real wheeler dealer that way.
So trading Marner in a short period of time shouldn't have been a problem. It's a simple matter of calling 32 GM's and asking if they're interested. Start with the ones you know would be in on him and go from there.
Once you got your short list of offers you call them back and squeeze them for more.
We're talking about a 100 point winger who can play in all situations. If you can't trade a guy like that in a matter of days then you're incompetent at the job. It might surprise some Leafs fans to learn this but, like Dubas, Marner is a hot commodity in the hockey world outside Toronto.
Someone will pay the price in a heartbeat.