The reason relates to the dynamics of the driller group. These dynamics change very slowly and then persist. Yet everyone thinks that things are about to turn, so the selling is not a cattle rush towards the gate. Actually, it's been my experience that slow rate declines are more bankable, and drastic declines (not price shocks or gaps that cut a stock in half) are more likely to turn around sooner.

The MACD lines cemented below the centerline in mid June. This means a constant rate of change down. The pace is approximately 1/4 point each day. You can see by eyeballing the 13-day and 50-day EMA's that they are traveling at approximately equal distances apart. Since MACD is derived from the difference between the 12- and 26-day EMA, the equidistant thing between these two happened sooner.