Matthews contract (and Marner contract for that matter) is objectively terrible. No one can defend that. You walk a guy right to UFA, buying only 1 UFA year but then also pay him like a UFA on his RFA contract? Ridiculous.
The entire point of the RFA system is to gain cap efficiency (or atleast that's how most teams in the NHL treat it), either by extracting term from a player well into their prime UFA years or extract short term cap savings, when you do neither that's a failure.
When Tampa signs a player short term, they always extract significant cap savings (Kucherov, Pointe, Sergachev), when Oilers paid Draisaitl for what looked like an overpay, they bought significant UFA years. If you are not doing atleast one of these things with your RFA contracts you are not putting yourself in a position to win in the cap era.