The Leafs have 3 second round picks for the 2017 draft.
They have San Jose's and Ottawa's.

They traded the best of the three (which will probably be their own).

Not a deep draft and the extra pick(s) are assets.

Replacing Smith and the not quite ready for prime time Gauthier they have upgraded their penalty kill, toughness and faceoff skills.

A good trade.
It isn't supposed to be a  Weber for Suban.,