When making changes to their organisations, managers often commit the error of being ‘architects’ without understanding the ‘plumbing’. Can you think of examples where managers have made changes only to make things worse?
Effective change requires sufficient knowledge of what’s happening now to make a prediction about what will happen when the change is implemented. And note that a ‘prediction’ is not the sort of thing you normally find in cost/benefit proposals.
Furthermore, even with knowledge you will be able only to predict the direction of improvement, not the absolute value (which illustrates why we should always distrust the firm claims we see in business cases and the like).
Getting sufficient knowledge means studying a system or process to understand more about what it is achieving and why.
Architects who assume they know the plumbing often cause havoc, making performance worse.