I think this all comes back to Leafs fans thinking that poll about being the best GM to negotiate with is a bad thing.
I have talked to a guy who represented an agency (and it was one that has a lot of Leafs clients), and a lot of the time it is not about getting top dollar and rather going to a place where they feel most valued. Sure, money plays into that, but it is also respect from management and the idea that, even if things don't go perfectly or maybe a change needs to be made, they will still be respected. See Leivo, Barabanov, Mikheyev... That is why Dubas ranks at the top of that poll; not because he is easy to negotiate for top dollar.
And in fact, the only real overpayment he gave out was Marner, and that is a direct result of him getting completely disrespected on his ELC by Lou. Now we can argue whether Marner should have felt disrespected, but it is irrelevant. He was a guy who wanted reconciliation from the position he felt disrespected him, and that meant making up that money on his next deal. If we take that money off, Marner makes about 1 mill less than he does now and suddenly it is not an overpayment (or at least not much of one).