Most realistic opinions that avoid trolling would say the Leafs have an average D. It's not the worse. Like I said before, The Leafs will destroy bottom 20 NHL teams but it's a different story when they face a top 10 team with offense and a solid defense.
IMO, from the outside looking in, the Leafs need a beast who is solid in his own end to play with Rielly. Someone Babcock can trust and play 25+ minutes a game. Expecting prospects to fill this hole is reasonable but that will take years.
I disagree somewhat with this. The Leafs took Boston to 7 games last year despite having some key players not performing or not on the ice. Boston is clearly considered a better defensive team.
Furthermore Babcock likes players to play specialized roles. It's largely so he can get the matchups he wants. Using specific players only on the PK means when the PP is over and the other team is throwing out their 3rd line he can put out any combination of Matthews, Nylander,Kadri with guys like Gardiner. People who don't watch the Leafs or have no understanding of that can sometimes think that means Babcock has no faith in specific players when a lot of the time it's solely about matchups and playing players to their utmost strengths.
The key to the Leafs defence getting better is most likely not getting a middle pairing guy. Nor is the option really there for a stud #1 to be traded let alone traded for. It's forwards coming back and playing responsible.
The Leafs top 4 is Rielly, Hainsey, Gardiner and Zaitzev with Dermott most likely on the verge of taking over middle pairing minutes. Hainsey was basically used as a PKer all year last year meaning bringing anyone in to replace him will also have to take on that responsibility. Doubt you want to pay a top line D to play the number of PK minutes Hainsey put up. Zaitsev had a bad year after injury so we'll have to see if he flounders still or improves to his rookie self or beyond. Dermott is obviously going to be the offense for the 3rd pair and with Oz starting the season we'll get to see what he can do. I'm not nearly as worried as some and think this D can take us past the 1st round if need be.
Especially considering the Leafs strength comes from their forwards they may be average at best at defence but they are top 5 in offence and specifically at Center. Even in the playoffs, having Kadri as your 3rd best center (as long as he is not suspended....) should be more than enough for most teams in the PO.