Here is something to ponder, even at 12M, Leafs could have Zach Hyman and Tom Wilson for that salary. If it's $14M, you have a couple of million extra to spare. I just pulled those two names off of the top of my head I'm sure there are even better options.
When the playoffs roll around, would any team rather have Marner or Hyman/Wilson in their lineup?
Marner is a talented guy, has the most impressive I've seen vision since Gretzky or Gilmour, it's that good. I'm watching the game from the birds eye view of the TV angle and he's still seeing the play unfold better than I can. It's incredible at times how he sees the ice from ice level.
He kills penalties, he strips pucks, he finds the open man, he's even shooting more. This years Marner is the best I've seen except for a few game stretches each year.
All of that said, it comes down to "will he (and the other core) show up when the pressure is amped up, the game gets physical, the ice is smaller and every shift in every game becomes magnified?"
The Leafs have been emulating the definition of insanity for nine years now, even when challenged by reporters in their year end excuse fests. They've been in their primes for a couple of years.
Because it's the Leafs, I expect them to overpay for him, give him a full NTC, and handcuff their team again so that they lose key players down the road, be it Knies, Benoit, a goalie or young up and coming player.