I think goal tending early was the clear cut #1 problem.
I think because of the that the defense looked worse then it was.
But as a defensive minded center, Zacha does get included in that defensive criticism. And I think that criticism is more that he needs to be better at, moving the puck up ice, maintaining possession, keeping the puck down the other end, creating chances and scoring goals. It's a little bit of the Lovejoy/Greene criticism. Sure they can defend, but if you can't push play, and are always defending, then you are going to give up more goals then you score.
Clearly he has more offensive talent then those guys, but it does boil down to the same issue in my mind.
So yes, when your #2 center is producing little to no offense, and getting hemmed in our own zone, I do consider that a major issue. And I am saying this as a big Zacha fan.