They're not up to the challenge.The forwards are improving their carries, there is no doubt about that, it is their defence that needs sorting now. Like one step forward and two back.
Pure and simple.
They can get their go forward working but at the cost to the defense. Or they can get their defense working but at the cost to their go forward. If they balance the two out evenly they get soundly beaten on both.
Better to look good at one aspect and give the coaching staff some false hope, than to expose yourself as the imposter that you really are.