In an evolutionary approach to macroeconomics, the market disequilibrium dynamics resulting from structural change need to be properly represented at the aggregate level. As suggested by the late F.A. Hayek, a suitable equilibrium concept required to this end as a frame of reference, is that of a flow equilibrium. The paper explores the corresponding flow dynamics that draw attention to variables not usually considered in macroeconomic theorizing. Using statistical estimates for these new variables for the West German manufacturing sector during the German unification process allows some important new insights on the relationships between structural change and macroeconomic performance.