Considering Bello's contract, Shaw is probably worth more in a trade due to how cheap he is. Bello would go up to 4/12.5 AAV or so. If he was still on an arb number, he may have more value in a trade than with the additional years of control. The years of control are good if you want to retain Bello and think he's going to outperform the deal (i.e. be a #2).
They should probably work out a deal for one of the OFers and Paredes as it makes sense for the roster, but HOU would probably rather deal for a pitcher if I had to guess. Sox overvalue Duran, so I wonder what it'll take to move him.