In theory that is how it should be done. But, because the bases aren't square, it doesn't hold true in application. Here's why:

If a defender was parallel to the LOS and was "spun" on his center axis to face up/downfield (perpendicular to the LOS), he would actually gain/lose yardage/distance to/from the ball carrier.

Pivot sticks or 2 Refs to box the player in on the 2 forward most edges is the fairest way to go. I am actually doing 2 Pivot Refs which I hope will make multiple pivots A LOT easier! Stay tuned.