well you play like a factory manager, and you use a list to see who is promoted and can fill the job , the other way is looking at the stat´s and missions/kills and promote because you like that soldier. Meaning during my playthrough i go back and forth to see if i want to promote that guy (they are always lot´s of options and it takes resources to do so, so i want to chose the guy with more mission/kill´s etc, that i know more about..) , and even if i filter by kills in transformations maybe not the rank i want for the guy.
meaning i want to advance a particular soldier and not fill the sergeant position on the factory.