The first requirement is to have clear insights in your business processes, IT and data as well as their relations and dependencies. A clear and accessible mapping of these assets is key for the ability to think in scenarios and determine the impact of alternatives.
ValueBlue recently executed a benchmark on the impact that Enterprise Architecture has on the total performance of an organization. The benchmark shows that most organizations spend a considerable amount of time (up to 70%) of large projects on gathering all required information about the current situation. That is time and effort that needs to be spend before you can even set up the different scenarios for improving and transforming the current situation. This hinders you from reacting quickly if the circumstances suddenly change.