Well a chunk and top is basically the same problem, combination of not having keys 1 - 3. Basically if your head moves you have to adjust the clubhead with your hands. If your weight isn't forward at impact, you'll flip at the ball to not chunk it. Both of those things cause the lack of having a flat wrist at impact.
Basically what that means is, you can't deliver the clubhead to the ball consistently. Same with chips. If the weight is 50/50, in such a short shot, then its tough to make a proper strike with out the ball being back in the stance. This causes a steeper angle of attack bringing in the leading edge, making it tougher to achieve good clean contact (the club can dig in the ground more).
Usually when a person gets in the habit of chunking or duffing chips or pitches they don't want to do it. So they will lift up and hit those thin shots. Then they wont want to do that, and they will hit chunks.
Its gets to be a vicious cycle.
so with chips, weight should or should not be 50/50 with ball back in stance? thanks