When you crown entitled kids as the kings of the city this is what you get. Say what you want about Babs, but he was the only person with Lou who tried to keep them on line.
Dubler Dubas and his soft aproach caused even more problems. Sheldon was castrated and couldn't send a message to players, because Dubas didn't allow him to do so. Now it's too late for him to change his ways.
The real problem and main villain is Shanahan. He decided to promote Dubas and dump Lou. Lou was a dinosaur, but it was too early to fire him. His work establishing a great team culture wasn't ready yet.
Leafs main problem is that they're player orientainted not team orientainted. Think of Florida, Boston, Canes or Vegas. It's is always about the TEAM, not a single player. You never hear that anybody to say that Slavin or Aho / Eichel or Theodore need to carry the team. Like you hear every day how Matthews needs to do x, z and y.
Fire Shanahan, Treveling and Co. Hire someone with huge balls that will buyout Nylander, dump captain silent to the moon and trade Marner to Utah. Spend next two years to clean this mess and try to find and draft players who will create and build a team culture where it's all about the Maple Leafs and nothing more. If Matthews won't want to be part of that then trade him.