The Penguins, who the Leafs most resemble, just showed what can be done with a defence made up without a star (Letang being out all playoffs).
They need to be very careful with what future they give up for any defenceman.
Shanahan, Lamoriello, and Babcock have all said the same thing that the goal is to build a perennial cup contender, you don't do that by trading aware futures (Kapanen, Brown etc..) or high draft picks before you are ready.
Long time fans of the Leafs will be very familiar with this type of mistake.
For Duck's fans if you can get Drouin from Tampa that would be a great return in my mind.