Concerning young D issues indeed, but is it the system or the players ? I’m not sure having a top 4 D (if it is ever possible now it is so expensive) will change the D system. NHL is punishing, a mistake = a goal, but if you can play following a good D system, with a lot of will, it should be enough. Look at the start of the season, it worked.
Maybe it is too demanding, and as the young ones are getting tired, they cannot follow it properly.
But I’m not sure a good D would bring better results. Unless they can bring a superstar like Lidstrom…