I think you could argue equally, we should have won two.
That said, Montas ... I'm sounding like a broken record with this, but I don't think starting pitching is one-half the problem, at all. I don't think starting pitching is even the concern. Sure, get better in that area if you can, not saying not (unless they A's still want an overpay, then definitely not) ... but I think the priority is the BP. With a better constructed BP, we don't lose the game on Wednesday, imo. That's not to say that every BP implosion results in a win vs a loss, sometimes there is just an off day, but there certainly would have been more converted wins if only.
And the other half of the problem is the inconsistent offense, but that's a different thread, and I don't have a solution, right now, for that anyway.
Bottom line, if we trade for Montas and we don't also get a couple of quality BP arms, there is no reason to trade for Montas at all. imo. It would be great to get both Montas and 2 quality BP arms ... but if we only go after one, we should go after the BP arms.