Reality is, it's always going to be tricky to go on a deep playoff run when you're sort of sifting through the discount bins for your goaltending. The last few years the Leafs have been particularly unlucky in that they've run into goalies destined for the HHOF in the first round. This year they finally managed to clear that hurdle but, realistically, if consensus around the league was that Samsonov is the kind of goalie the Leafs need him to be, they wouldn't have been able to sign him for what they signed him for.
There's still time for him to prove that wrong and this series could easily flip if the Leafs top lines start producing but they've made things very tough on themselves now.