This is not Matthews' first go around in the playoffs. He's had seasons where he's put up (slightly) better numbers, but he's never driven play, he's never taken over games, he's never used his size to get into the middle of the ice or go to the net, he never engages.
All of the things you say about Tavares hold true for Matthews.
Toronto has added a ton of compete over the years. Now they have Nylander, Knies, Tanev, Laughton, OEL, McCabe, Carlo, Benoit and Domi surrounding that core. All high compete, "character" guys. In years past, it was O'Reilly, Foligno, Schenn, etc.
Matthews plays the same way he always has.
And you're right they should definitely swap Marner and Tavares out for two "harder" players.
But when they do that, those players will compete, but Matthews will keep playing the exact same way. Unless they're somehow bringing in a Mark Stone or Matthew Tkachuk, I don't see anyone who will come in and "elevate" Matthews or change his style of play or temperament. Even those guys might not do it.
He doesn't have another gear, or is not willing to go into another gear, and it's high time people stopped blaming everyone but him. And when you're making $13.25M... that's a big problem.