As an attempt to prove the well-known shuffle conjecture, Haglund, Morse and Zabrocki introduced a family of symmetric function operators which are closely related to operators of Jing. Jeff Remmel at UCSD and I studied the combinatorics of these operators. In this talk, we explain the Schur coefficients of these operators applied to Schur functions. This combinatorial method gives a new recursion for the Kostke-Foulkes polynomials.