This comes to my mind after I read all the wiki pages that out of all Strangereal player characters (excluding Nemo, who is an A.I.), it seems that Mobius One is the only one whose military rank is never stated / addressed.
I thought of several probable things :
1. He might be wearing a naval officer rank, since by the way he began as a carrier-based fighter pilot, he might be (and perhaps the only Ace Combat player character) from the Navy branch (all of the other player characters are from Air Force branch).
2. Since he made his debut as a rookie, Mobius One's starting rank at the beginning of AC04 might be either Ensign or Lieutenant junior grade / Sub-Lieutenant.
3. The way he quickly rose to fame throughout the Continental War and the respect he earned from ISAF, I think that his last known rank is either Lieutenant Commander or a Commander.
What do you think ?