Definitely - Yes they could, but when recommissioning a plant...

Definitely - Yes they could, but when recommissioning a plant its common practice to chuck a known low-grade feed through to make sure all the crushing and screening and then fine-tuning reagents etc. They seem to suggest and I understand its common practise that once the mill is in a steady state then that would be the time to blend in the higher-grade stockpiles with the low grade to bring it up to a target range. Its often difficult to measure the grade of stockpiles of ore that are from narrow high-grade style mineralization as they are often locally very heterogeneous with variation in grades at the grab sample level.