Early 1-2, 2.33 ERA (as a starter)
Sandoval 18-49, 4.01 ERA (as a starter)
Dobbins 4-1 4.25 ERA (as a starter)
Oviedo 13-26, 4.39 ERA (as a starter)
Crawford 16-29 4.69 ERA (as a starter)
Tolle 0-1, 7.84 ERA (as a starter)
To me, Early, Sandoval and Oviedo are competing for the last two spots going by what you posted. Considering the cash outlay and lack of options, Sandoval is definitely getting the first crack at the 5th spot in the rotation at the very least. Maybe he flames out? Maybe he's not ready and is phantom IL'd to start the year like we've seen with Bello, Giolito and others recently?
I do wonder about the idea of moving Bello in a trade for a #2 rather than Tolle or Early.