A noteworthy quote in this piece from the Gregs:
“I call him Mr. Petraeus because he’s less of a general and more of a politician,” the official said, alluding to rumors that Petraeus might run for president. The Pakistani official spoke on the condition of anonymity because the interview dealt with sensitive intelligence matters between Pakistan and the United States.
This is also why it made sense to send Petraeus to CENTCOM. You deal with the leaderships of authoritarian states. Natural mirror-imaging makes them more likely to respect and listen to men with stars on their shoulders than to civilian diplomats. (It's part of what makes rebalancing civilian and military components of national security so difficult.) That's all the more true of nefarious leaders of intelligence services, the men with blood on their hands that the CIA is entrusted to deal with. They see a man like Petraeus in the CIA job and conclude: ah, so that's where the center of American power now resides.