I watched every playoff victory of the Leafs against the Sens when the Leafs were a big, bruising, physical team. Those Ottawa teams were stacked with young talent but they didn't have the heart. I watched Roberts run over a young Chara, it probably helped Chara to realize being a big guy requires some fight. Leafs beat them every year, four times in a row they met them.
This is an entirely different league now. I've raised this often, watch the 2002 Leafs vs NYI series. It's the only series I watch from time to time just as a reminder of how violent the sport used to be. It was the most brutal series I've ever watched and the Sens faced a limping Leaf team due to that battle. A team I thought had the right playoff types to win but that First Round against the Islanders just crushed them
Anyways, I think there is an opinion that the Leafs are a soft team this year and somehow Brady is going to try and run the team out of the series. It's not going to happen. Leafs aren't some physical juggernaught but they are far more comfortable with physical play, sacrifice and even fighting (most number of different players in the league of any team who fought for Toronto this year, who had that on their bingo card?).
Berube has driven into them that they must stand up for each other and they have. It should be a good series due to geography but Leafs play a tighter game than in the past and they have 6 players with over 20 goals, so any mistakes by Ottawa could be costly.
If the Leafs special teams is rolling they should win this. If Ottawa can figure out the Leafs defense, they will squeak out a series win due to higher scoring games than one might expect.