If the Phillies had left Pivetta in AAA, he'd been in the top 5 in the Int'l league. He was blowing everyone away when he was called up.
This is the weak spot of ratings, if you graduate a lot of players quickly, it makes your farm system look worse.
Phillies have promoted a lot of players the last two years:
2017: Crawford, Alfaro, Hoskins, Williams, Pivetta, Lively, Knapp, Leiter, Milner
2016: Thompson, Velaquez, Eflin, Ramos, Joseph