Miracles are, in fact, the common coin of Sufi hagiography. They occur in a vast variety of forms, ranging between relatively simple instances of knowing the past or the future, and spectacular performances that can transform the material world.
The idea that miracles are a common coin of Sufi hagiography tells me that it's been an ancient teaching and something referenced for a long time. Miracles would occur in many forms which I personally think is a very powerful fact because that means anybody could experience one. There is a miracle story within the past, present and future. It's apart Islamic history and how people's beliefs are shaped.