Foata and Zeilberger defined the graphical major index, maj ′ U , and the graphical inversion index, inv ′ U , for words. These statistics are a generalization of the classical permutation statistics maj and inv indexed by directed graphs U . They showed that maj ′ U and inv ′ U are equidistributed over all rearrangement classes if and only if U is bipartitional. In this paper we strengthen their result by showing that if maj ′ U and inv ′ U are equidistributed on a single rearrangement class then U is essentially bipartitional. Moreover, we define a graphical sorting index, sor ′ U , which generalizes the sorting index of a permutation. We then characterize the graphs U for which sor ′ U is equidistributed with inv ′ U and maj ′ U on a single rearrangement class.