Performance management within government is at a crossroads. The advent of big data, and advances in technological and analytical tools have provided opportunities to measure and track a wider variety of internal and external indicators on a more timely basis. Public leaders require new vision and capacity to design and manage knowledge-building systems. This paper provides two tools: 1) a more comprehensive open systems performance management framework, and 2) a model of leadership needed to orchestrate such systems-- knowledge brokers -- who orchestrate both the demand for and supply of evidence. This paper recommends that public agencies strategically build evidence to better: track measures of the effects of governmental actions on public value, and intended and unintended consequences on the ecosystem; articulate, measure and test the assumptions built into their operating models; and learn from routine monitoring of the dynamic environment in which their organizations strive to achieve their mission.