I don't see how Arizona can win if they pay Matthews an amount the Leafs won't, unless they become an NHL cap team. I don't think any NHL team can pay a player a close to 20% of there full salary and win. If Arizona keeps the same budget they have now, or even just slightly increases, but allocate that money to Matthews they will still have significant issues winning. Matthews helps you win, but only at a certain price-point, or as a certain percentage of your salary expenditures.
Let's assume Matthews gets 17% of the cap (slightly more than what McDavid gets right now on a deal he signed as an RFA). Right now, Arizona has 9 million in Cap space. That's before realizing they have only 64,000,000 million (roughly 16 million below the cap) in salaries expenditures. Then factor in that 80% of Hossa's and Booth's contract is covered by insurance. So, in reality, Arizona is spending about 56,000,000 in actual salary. Paying Matthews 17% of the NHL cap would account for 13.6M under the current Cap, but on a team like Arizona that would account for roughly 25% of their salary. I don't care if its Gretzky in his prime, I don't think any NHL player could help a team win when he accounts for that much of the team's salary expenditure. Getting Matthews won't immediately make it viable for them to spend to the cap.