I do not understand the hand wringing over this. Toronto has to pay him, you can't play hardball with a player of this calibre. Him leaving your franchise is infinitely worse than "overpaying" him. What's more, I don't even know that they're really overpaying him. He makes slightly more than Mackinnon and McDavid, it's not like he set the new AAV record by 4-5 million dollars. It's less than a 3 million dollar raise fromvhis RFA contract. I think all of those guys are so valuable that even if they were given the max AAV the cap allows they would still be worth it.
Additionally, it's obvious based on his post ELC deal and now this one that Matthews is trying to maximize his earnings. Friedman (?) said his camp was unwilling to go longer than 4 and even pushed for 3. IMO they were never going to budge on that, so I think you just be happy he's not headed to UFA potentially ending any contention window the Leafs have.
I hate the Leafs but I'm not going to clown them for paying what they had to in order to keep one of the NHL's best players.