#delta_smooth_rod_offset controls the "dishing" of your hot end. Ideally, if it's set up right, then you won't have any dishing and everything will stay nice and level as the hot end moves around. It doesn't effect the nozzles height at X0Y0 (centered). It will will effect the Z height at X0Y50, X-30Y-50, and X30Y-50 which are three good test points for dishing.