At the end of the day, your best players need to be your best players. The Leafs didn't get that, but the Habs did. Even Gallagher, who was mostly silent throughout this series, came through in the clutch.
Also, just for fun I had a look at the top 5 point getters on each team that is currently in the playoffs. I think, with the exception of perhaps Vegas and the Isles, it proves my point:
Toronto: 1. Nylander, 2. Kerfoot, 3. Spezza, 4. Matthews, 5. Galchenyuk
Montreal: 1. Toffoli, 2. Perry, 3. Armia, 4. Staal, 5. Suzuki
Colorado: 1. MacKinnon, 2. Landeskog, 3. Rantanen, 4. Makar, 5. Graves
Boston: 1. Pastrnak, 2. Bergeron, 3. McAvoy, 4. Marchand, 5. Krejci
Tampa: 1. Kucherov, 2. Hedman, 3. Killorn, 4. Stamkos, 5. Point
Carolina: 1. Aho, 2. Necas, 3. Staal, 4. Pesce, 5. Svechnikov
Vegas: 1. Janmark-Nylen, 2. Stephenson, 3. Tuch, 4. Stone, 5. Karlsson
NY Islanders: 1. Beauvillier, 2. Pageau, 3. Nelson, 4. Bailey, 5 .Palmieri