At the end of the day, the ARPA model depends on program managers.
These individuals play an important role, traveling throughout the layers of abstraction of a given project, as well as communicating and coordinating information and tasks amongst these different layers.
One of the key properties of this individual is the ability to deliver results in the face of uncertainty, or ambiguity.
PM's Pull Control and Risk from Researchers & Directors.
Control
Risk
The Best PM's Notice Systemic Bias
A Large Part of a PM's Job is Networking
PM's Need to be Freethinking, Curious and Humble
DARPA is Flexible about Hiring PM's
DARPA PM's Have A Tenure of 4-5 Years
Why do people become PM's?
When sourcing PM's, assessing this motivation is one of the ways to avoid overlap with other "high variance" industries, but there's not lot of structure to the process of selecting talented individuals for this position.