-Fuentes: great stuff, still young, eventual rotation mainstay (but maybe not this year)
-Waldrep: good potential, but coming off surgery; no guarantees
-Ritchie: good potential, needs more experience
-AJSS: coming off TJ surgery; even less of a guarantee than Waldrep
-Schwellenbach: Hasn't pitched in a full year, no idea when he'll be back or what he'll be able to do
So, yes, they need multiple starters unless they're willing to gamble on the internal options being good/great right away.