Noah Shactman has an interesting post on the Danger Room Blog at Wired noting that the Pentagon has “reprogrammed” $32 million of DARPA funding, including $2 million from the Information and Communications Technology account because of DARPA’s inability to attract program managers and spend the money allocated it. From the Reprogramming Action (pdf) report:

“DARPA continues to underexecute its Research, Development, Test and Evaluation programs for two reasons: first, several key program managers’ positions are unfilled because there are few experts in advanced sciences and technology, and second, DARPA’s approval process is delaying contract awards.”

If I had to guess, I’d say the latter reason might have something to do with the former, too.
It’s certainly possible that the same policy changes at DARPA that have made it more difficult for university researchers to work on DARPA problems have also made DARPA a less-desireable place to spend a few years, but that’s just my speculation….