The heeler has quite a bit more to think about than the header. The following is a description of good positioning for a heel shot.
In the best of all possible worlds, for a good run, the steer will leave the chute and run straight in a left lead. To help ensure the steer departs on the left lead, the steer should be hazed a little toward the left. The heel horse will be about 10 feet to the right of him and will have his head alongside the steer's RIGHT hip.
Once the steer has been headed and is being turned to the left, the heel horse should tip his nose to the left a little and his body should be in the same position as the steer's, as though mirroring the steer's movement. That is, as the steer is being pulled to the left, the heel horse should cross behind the steer so that the horse's head is now at the steer's LEFT hip.
After the steer is again straightened out in a line, the heel horse should remain in position to the side of the steer's left hip, setting the heeler up for easy speed and accuracy.
Such positioning allows the heeler to better help direct the steer's movements and will give the heeler enough space to make whatever slight adjustments might be necessary in the moment; yet without ever getting out of position for a good heel loop.