He was certainly the greatest "research manager" in his field, and because of this had the largest influence in a time of the greatest funding for computing research. It is impossible to overpraise his impact and to describe just how he used his considerable personality to catalyze actions.
The key idea was to have a great vision yet not try to drive it from the funders on down, but instead "fund people not projects" by getting the best scientists in the world to "find the problems to solve" that they thought would help realize the vision.
An important part of how this funding was carried out was not just to find the best scientists, but to create them. Many of the most important researchers at Xerox PARC were young researchers in ARPA funded projects. Bob was one of the creators of this process and carried it out at ARPA, Xerox PARC, and DEC.
He was one of those unique people who was a central factor in a deep revolution of ideas.