Something just crossed my mind. Since we're on this topic, are there subtle but powerful effects that rank has? Maybe you can't build another base until you have a captain? Or maybe other factors. As far as I'm concerned rank means more responsibility and a need for certain leadership qualities which doesn't necessarily mean excellent shooting skills.
Just brainstorming. Maybe higher ranks can call in air strikes from nearby interceptors. Ok, so the aliens are already at a disadvantage, but small things like that. Like the authority to destroy a crash site from the air.
Just a thought. Feel free to share your thoughts.