I have the line valued at -172/+172, so the market appears efficient here (which should be expected heading into the close). The DBacks are being priced somewhere inbetween current form and true potential, and there is no fundamental reason for the DBacks to be struggling more at home (thus lacking sustainability).
A better question you should be asking why you want to lay money on something you are perceiving to be -EV (or at best 0 EV).
