Who decides strength management per MOS and how does it work?

Without a per MOS annual newsletter explaining what are the strengths and challenges of each MOS it becomes hard to understand where my MOS is going moving forward. It also makes those with insight information have a huge advantage because if they know that a big change is incoming such as an MOS shirking or combining, they can make well informed career decisions such as reclassing or applying to positions that would eventually become extremely competitive based on a case by case scenario