In a recent conversation with Seamus Heaney, I made the point that after Roy Foster's monumental biography of Yeats, any further efforts at biography had been well and truly silenced. The advent of Bill McCormack's book, Blood Kindred, made me think again.
Can you help me with understanding the meaning of the bolded passage? Is the meaning that Foster's biography is so great and brilliant that any next try to write a new biography would hardly overcome the one written by Foster? If so, why the past perfect ("had been well and truly silenced") is used?