The US military has subtle mechanisms that would not be obvious externally. I'm sure it varies and changes, but something as simple as the timing of an officer'

The US military has subtle mechanisms that would not be obvious externally. I'm sure it varies and changes, but something as simple as the timing of an officer's promotion, or review without promotion, can signal an "end of career" event. Someone familiar with the branch and with access to the promotion data could tell you if an officer in the chain may have been held responsible. (A view from the outside, but not far outside.)