But as for what can be done with simple tools, anyone with a basic Geometry background knows that you can construct almost any pattern with great precision...Furthermore, the "geometric precision" of crop circles is often overstated."
Not trying to be hypercritical, just trying to get some insights.
FWIW, it is indeed possible to create patterns of great prescision, but in the actual execution, sometimes mistakes happen. Pehaps the circlemakers overestimated the size of the field, and had to compensate "on-the-fly".