Holding Matthews, Marner, JT, Nylander to a dollar value that allows you to build a sold team is called doing your job. There is no rule that says you have to keep every player you draft, or you have to give every player whatever they want in contract negotiations. If a player puts getting paid the most or near the most in the league for his position and that puts you as a GM in a position where you cant build a strong balanced team, then you as a GM have to decide which trade offer you are going to take for him.
Nylander was a gift horse for Dubas and he messed it up. Your negotiating position is this, this is as high as I'm willing to go, take it or expect a trade. If Nylander was traded, it would have sent a shot across the bow of every player that was going to negotiate with Dubas. Kap would have not got 3 mil and change, AJ would have not got 3 mil and change, Marner would be below 10 mil, so on and so on and so on, eventually you save enough where you don't have to trade Kadri, you don't have to let Barrie walk, you have room to comfortably negotiate with Hyman.
If you want to be a Leaf this is my price, if you want to be the richest at your position, nice meeting you, have a nice career in Arizona or where ever. It does not make the player a bad person that they want to get paid and it does not make the GM a bad person he wants to stay with in a responsible cap number.
Hey right now I'm negotiating on Kijiji for something that is basically brand new, new it cost 3000, he was asking 2100, I offered 600 to start, he came back at the lowest he will go is 1500, I came back the highest I will go is 1000, I really want what he is selling but I know he will eventually cave because he wants to sell it more than I want to buy it. Same concept for Dubas, he wanted to buy it more than the player wanted to sell their services to Toronto, so he was always negotiating from behind and now he's dropped his pants for the last 7 signings, he has no leverage in any future signings. You have to know your opponent in any negotiation and you have to be willing to be patient..