How is it even possible to advance to flag rank without having received one somewhere along the line?
It has to be hard. He does wear the Vietnam Service medal, but that was a little before by day, so I'm not sure exactly why he doesn't also have the CAR, but he clearly doesn't.
There haven't been a lot of Navy CJS. I think only three or four. Most of those were naval aviators, with heavy combat experience from WWII. Crowe, who served under Reagan, wasn't an aviator, but he had heavy surface warfare experience, again during WWII. Mullen came in during the tail-end of Vietnam, and was never deployed to a ground unit, like a Seal or FO, or to a literal ship like John effing Kerry. Mullen is/was a pretty conventional surface warfare guy serving in a navy that hasn't had a large surface warfare battle in almost 65 years.