The stacking of blacks in noncentral positions is a time-consistent feature of professional baseball. It is shown that differential batting and slugging averages between positions are also a structural feature. The structure of stacking as well as its evolution are well explained by the uncertainty thesis, that is, the belief that discrimination and differential barriers to entry are linked to the difficulty and lack of objectivity in assessing player performance at a given position. However, because the uncertainty thesis fails to predict the expected performance differentials between black and white players, auxiliary hypotheses have to be entertained. It is concluded that a combination of the uncertainty thesis and the well-known centrality hypothesis may best explain what occurs in baseball.
Marc Lavoie is with the Department of Economics and School of Human Kinetics, University of Ottawa, 550 Cumberland St., Ottawa, ON, Canada KIN 6N5. Wilbert M. Leonard, II, is with the Department of Sociology, Anthropology, and Social Work, Illinois State University, Normal, IL 61761-6901.