So Greer is somewhere between 25-30 years old and an E-8 already?
Yeah, that is definitely too fast. Particularly since he does not seem like a political minded ambitious ladder climber. With his anger issues it would seem like just the opposite, he should be having trouble getting promoted on schedule.
In my experience in the Army, if you were a really sharp high speed dude and joined at 17-18 years old you could make Sergeant First Class(E-7) around 27 or 28 years old, but unless you had some friends in high places getting your E-8 before 30 was impossible.
But Greer is nothing like the rapid promotion guys I knew in the service, which just makes it even more outlandish.