Reconnection of magnetic field lines at a neutral line that forms in the near-earth region of the plasma sheet at substorm onset creates, from some longitudinal sector of the plasma sheet, a plasmoid that is then free to flow out of the magnetotail into the magnetosphere's wake. The magnetic field in the departing plasmoid frequently displays a strong positive or negative YSM component that has been difficult to reconcile with the reconnection geometry as it is traditionally depicted in two dimensions. We show that this deviation of the magnetic field is a manifestation of a draping of the newly reconnected field line loops toward the tail's central (midnight) meridian and that the draping is a consequence of the three-dimensional plasma flow associated with the reconnection process.