I see what you are saying and certainly we can always use improvements on that line, but I wonder how much was the DL looking bad because a LB wasn't in place to make the play that they were set up to make. It sounds like the goal of these stack schemes is to have the DL just take up space so that more athletic filler guys can come in from behind and make the actual tackle. We really really lacked that with the LBs this year.
The goal is mostly to confuse blocking calls/assignments by stacking the LBs behind the DL then having designated post-snap responsibilities.