  We examine the "naturalness" of the scaling of multiplicity and elliptic flow
$v_2$ with rapidity in weakly and strongly coupled systems. We show that
multiplicity scaling is relatively straight-forward to incorporate in existing
ansatze with no unnatural assumptions, and argue that this scaling is
relatively insensitive to the transport properties of the system. On the other
hand, we argue that the observed scaling of elliptic flow observed is
problematic to describe within a hydrodynamic model (the Knudsen number $K \ll
1$), but arises more naturally within weakly coupled systems (where the Knudsen
number $\sim 1$). We conclude by an overview of ways proposed to make weakly
coupled systems compatible with the absolute value of elliptic flow, and by
indicating experimental probes which could clarify these issues.
