We provide evidence for heterogeneous game outcome uncertainty (GOU) effects across teams in Major League Baseball. Using attendance data from 2013 to 2019, we explore functional data clustering techniques and allow for nonlinear relationships to detect common patterns in predictive margins of team-specific winning probability. As a central result, we identify five groups of teams with similar GOU effects. However, only a few teams show GOU effects that resemble the typical hump shape that is postulated by the uncertainty of outcome hypothesis; the largest cluster is comprised of teams with fans whose attendance behaviour is relatively insensitive to differences in GOU.