Your posts are better suited for the Fire Keefe thread,
.. You've already gotten your wish there, and we're all 100% behind you there,
I regards to Marner he hasn't had one bad playoffs he has had many of them and its is a big reason at his Cap Hit why the Leafs are out in round #1 each year.
In terms of the new coach Marner is among the most obvious players on the roster that doesn't fit his big, heavy, gritty style play we're expecting to see deployed, so the regular season matches playoff style hockey more then the night and day strategy Keefe deployed. I will agree that playing run and gun hockey during the season and then tight checking hard hitting dump and chase hockey come playoff time is a fools errand if one expected you could just flip a switch and suddenly change strategies.
So while you in the right ballpark, with your position, you also need to think about what type of player personnel Leafs need to play successful dump and chase and neutral zone trap physical hockey to win the Cup. Its not only about the coach is also about player size, playing style and willingness to sacrifice for the sake of the team to move forward, Marner is a square peg in a round hole if you expect him to suddenly finish checks and win physical puck battles in a dump and chase type system. IMO.