The wing's defensive responsibility is to cover the point man and be in position for the breakout to start. That's about it. If a winger is making a big impact in the defensive zone, that typically means he's leaving his position to cover someone else, which means trouble is brewing.
If Zucker isn't doing his job, it's things like reading the breakout passes, flying the zone early, not getting himself open, straying out of position, turning the puck over, etc. And I don't think he's had nearly enough games and opportunities to even start writing the book on his play in the defensive zone.
If you're playing with centers and defensemen who aren't good at recovering the puck and starting the breakout, you're going to look terrible. Look who he played with last year.