The one mistake in the article is the elite prospect age path - it's a LA age path. HS players tend to start in rookie at 18, jump to A ball at 19, then progress level by level.
College juniors come in to the minors usually at 21, and often start in high rookie to get acclimated their college year (and for many college pitchers, to basically get a feel for MiLB ball, b/c they may have been overused). 22 in A ball (even if they start in A after college, they'll go to A+ the next year), 23 in AA, 24 in AAA/ML.
AAA teams fill out their bullpens and maybe the back of the rotation with AAAA types, and some of their bench spots, plus any spot where there isn't a top prospect. Guys like C Ramos (33), Venditte (32), Beato (31) are buffer arms that can be called up if needed. Murray (27) and Mariot (28) are former prospects who couldn't stick in the majors. Leiter is a year or two away from joining them. Moore (28), Florimon (30), H Gomez (28), M Williams (28), are "hamburger helper", guys who man the bench. H Martinez (27) is moving from prospect to HH.
You see a lot of these guys in AAA b/c they allow you to not rush guys who aren't ready, but also provide a "reserve army of the undertalented" who can fill in at the ML level as "below replacement" replacement players for short periods. AAAA players who are replacement level or a little above don't last in AAA ball, as injuries and player movement open up opportunities.
At Reading, there are few of these guys, mostly emergency fill-ins. What you'll have are older, marginal prospect guys whose upside may eventually be AAAA players - Flores (25), Stankiewicz (24), Tomscha (26), Rickles (27).