A rotor assembly that has a support tube having a first diameter, at least one tooth coupled to the support tube, wherein the tooth rotates with the support tube to direct crop toward a chamber, and an undershot auger having an auger flight extending radially away from an auger core, the auger flight configured to cause the crop to flow towards a bale chamber region of the rotor assembly when rotation of the rotor assembly causes the crop to flow under the rotor assembly. Wherein, the auger core has a second diameter that is greater than the first diameter.
