Purpose – There is a great divide between the degree to which academic research accounts for the role of managerial discretion in firm performance and the weight given by the popular press and financial community to the importance of the management of an organization. The purpose of this paper is to bridge this gap by quantifying the way managerial beliefs influence the quality of firm performance in a turbulent environment based on e-business. Design/methodology/approach – An e-business research setting is used that is associated with a situation of environmental turbulence to allow for sufficient variance in managerial beliefs to measure their effect on firm performance. The sample contains 293 firms. Findings – Aggregate level results indicate that managerial beliefs have a positive and significant effect on firm performance. Four distinctive segments were also found to exist. These segments vary in terms of the strength of the position that a manager holds regarding the value of e-business and firm performance. Originality/value – The paper shows that the affect of e-business on firm performance is not structural in the sense that firm performance does not depend on the firm or industry but is reflective of the strength of the beliefs held by managers. This implies that the “black box” approach that is characteristic of much management research may be problematic because it fails to measure the variables that may matter most to performance.