What the Toronto Maple Leafs Need to Win the Stanley Cup
A Franchise Goalie : You can win the Cup without one, but you have a better chance if you have a franchise goalie.
The best goalie the Leafs have had in a decade is Freddie Andersen, and frankly, it hasn't worked out going with B-level guys. It makes the team too reliant on the offense. I think the Leafs should go all-in to trade for a star goalie.
Admittedly there aren't likely to be many options here, and this is a classic "easier said than done" situation, but they at least have to try.
A top-line Left Winger: Matthew Knies is a great prospect, but he's not ready for a 1st line role. Eventually, the Leafs will be glad to have him, but for now they need help.
After having Michael Bunting and Zach Hyman in that role for the last six or so years, the Leafs are spoiled. Those guys made almost no money, and once you put them with Matthews and Marner they became franchise level players themselves (at least 5v5).
That can't be matched or topped, but a star winger is a much needed addition. Knies on the third line after a potential star first liner and Tyler Bertuzzi would be incredible depth.