OK... I know generally that there is a period of time that a guy in AAA will bounce back and forth (filling in)between AAA and MLB at least for a few years up to maybe 8 .... is that not the time you are evaluated and then either given a number or told "thanks for coming out" with a pat on the back?
So guys going from AAA to MLB don't generally just get moved up (I think) without a few years moving up and down, and going through an evaluation period in the BIGS, this would also includes Spring training...
I only know a few guys in MLB and the Minors and they understand that once you get a number your in but getting there you are under a microscope...
Again my 2 cents...