I haven't seen him in minors but what he has shown thus far in majors indicates me that either he is not ready (and is far to be as I see it) and/or his stuff is just poor. Minors and majors are two very different worlds.
I have seen a lot of debuts of pitchers who are still kids and they step up since day one while showing what I call great stuff —command, control, dominance and a great repertory. Sorry but I just don't see the later on Bello, at least not yet.
Said that, hopefully he improves and can make the rotation. We need pitchers badly.