Yeah, even the guys who seem to be developing well always hit a wall or it doesn't translate to the majors.
I assume they'll add a mid-rotation veteran next year and then have Rodriguez, Francis, and Bloss fight it out for the 5th rotation spot. Something like Francis as the 5th starter, Rodriguez as a long-man/spot starter, Bloss opening the year in AAA with Macko moving up to Buffalo. Then Manoah and Tiedemann come back around the All-Star break and the starting depth starts to look pretty good.
They need a couple big arms for the bullpen, though.
Considering the way some of the other guys are playing (Clement looking solid with the bat and excellent defensively, Jimenez adjusting pretty well to the majors, Orelvis looking great in AAA - though obviously he's a wild card at this point, even Kasevich adjusting well to AAA) I think trading Bo to address multiple other areas might actually be a smart move as opposed to just something they're forced to do because of his contract situation.