In terms of prospect status, I consider 23 right at age/level for AA and anything younger is a bonus (21 or 22 in AA is usually a good sign). But, I try to consider everyone, because we see older players that are written off due to lack of prospect status become legit MLB talents all the time. Look no further than Mitch Haniger, or Ryan Schimpf for recent position players. Relievers are also different since most minor league relievers aren't considered prospects. You see MiLB relievers between 27-30 come up and have success regularly. Also, I don't write off players who have proven themselves to be elite hitters in the upper levels of the minors (but may have struggled in MLB, or not been given a shot). Those guys are always a click or two away from figuring it out. For players who are too older for the lower/middle level minor leagues, it is purely wait and see if they can perform at the upper levels of the minors to decide if they have a chance in the majors or not. If you are 23 or 24 in short season ball, the chances of this player making the majors are less than 1%.