Each military service has distinctly different Officer Evaluation Systems. Generalizations don’t work. Each has different requirements. I reviewed them all when I was the Head of Officer Evaluation and Career Planning at HQMC 1990-1992. Anything that deals with specific metrics is doomed to failure as is a grading process that rewards the measurable but not the intangibles. The key in a system of determining the most highly qualified from the highly qualified rests on reporting on the character of the individual in a narrative fashion. The longer an officer serves the more a full picture of his service, performance and potential emerges. Promotion boards are not idiots. They can read between the lines. I am opposed to a 360 evaluation process. Too cumbersome and filled with pitfalls of every imaginable sort. The immediate supervisor or commander evaluates and his senior reviews to place the report in a larger context.
The promotion systems of each service work fairly well as do the time in grade set points for each service. Start promoting water walkers too fast and you create many more problems than you solve.
That said, the systems work fairly well through Colonel/Captain (USN). All bets are off at that point.
There is an officer bloat. Far too much bloat in the AF, Navy and too much in the Army. From my perspective at the time I would estimate too many 0-4 to O-6 in the AF and Navy by 35%. The Army by 20% and the USMC by 7%. Many of these billets could be filled by limited duty Officers and Chief Warrant Officers.
The Flag Officers bloat is obscene. Probably 50% too many is every service except the Marines where it is about 20%. Many Flag Officer billets could be filled by senior Colonels/Captains. The real problem is at the three and four star level. These are highly talented and intelligent individuals. The political influences at these levels are not for the better. This is where the well is often polluted. Our Republic did not want the military intruding into politics but overlooked politics intruding too far into the military.
Where the nation has really gone off of the rails is in the selection of the Secretaries of Defense and the Service Secretaries. The exceptional ones are far too rare. Most have been nothing short of mediocre at best. The truly terrible out numbered the exceptional at least three to one.