Insiders have an ideaof what to expect from the drill results. Unlike gold which occurs in parts per million, copper can be measured in parts per hundred in a succesful hole. This means that the geologists that have analyzed the drill core can estimate, based on a visual inspection, the percentage of copper in the various zones as well as the width of the zones. You can be sure that word has gone out to certain people that the results are at the very least, encouraging, hence the big buying last week. It may still be many weeks before the lab results are out.
That is my take on what is going on.