Hainsey & Z & Polak as 50% of your top 6 D isn’t going to deliver good results, need to improve their D big time and give Andersen some support in the D zone. Their whole right ride on D is bad....really bad.
Andersen has been awful though, no question. .880 vs .926 (Rask) is absolutely glaring, especially when the microstats through 4 games show it's been very close (we actually had far better posession, scoring chances, and superior expected goals in game 2- I know it's not a solace at all but 4 goals in 5 shots, with at least 3-4 of the goals being questionable gives you no chance from the get-go). Eye-test for me matches as well. Leafs outplayed the Bruins over the course of last night, you just get zero margin of error when the goaltending matchup is that one-sided.....I think the D is passable->good against lesser teams but it doesn't stand a chance against the top teams in the league- and the Bruins are that (called them as the best team entering the playoffs, few times over, even before the matchups were set).
I think the team has gotten exposed in some ways because Boston has an elite-top end, are an elite-team, and don't have many weaknesses at all. The Leafs have the team to compete with that, but they have minor holes, top to bottom.
As for the D culprits who have been underwhelming, I think you nailed them Hunter. Though I think Z has been solid in the playoffs, just made 1 bad read on an odd-man rush. Hainsey as your top-pairing D is not good enough though.....only looks passable out there because of Rielly. With Gardiner, I think he's fine.....he's a risk-reward player, you just need to shelter him with better stability and Z isn't that yet (still think it has potential). This team desperately needs a higher-end #1/#2 that provides stability and someone like Polak, but better, who plays the shooting/passing lanes better. Gardiner is a guy you can perpetually look to upgrade on, but I don't think he's nearly the fundamental problem some fans suggest.
No they just don't have a good defensive core at all. Haven't even been mildly impressed with Gardiner or Dermott.
Dermott has been fine->good, should be a staple in the lineup for a while. Gardiner is what he is, he's good enough to be worked around. The issue is we don't have the proper pieces to shelter them, particularly on the right side. You have the right idea about what the problem is- relative to being a cup contender, but picked the wrong culprits, IMO.