This article applies a panel data model with observed common factors to Major League Baseball (MLB) data from 1904 to 2012 to analyze attendance. In particular, it aims to identify common factors. The empirical results suggest that MLB fan preferences were simple in the early years (1904-1957) with respect to common factors and then became multifaceted in later years (1958-2012), because the number of significant common factors increased from four to seven. Time trends and per capita gross domestic product were significant over the whole sample period, but outcome uncertainties and offensive performance, such as slugging performance, became newly significant common factors influencing attendance in later years. This indicates that fans consider not only their home team’s characteristics but also the characteristics of the away teams; then, in the modern era, it became critical for the league to implement elaborate business measures to promote competitive balance and slugging performance.