I agree with @Vanimal46, I think it has to be Maeda. Especially given the injuries to the rotation. The injury may have forced their hand to go out and get Mahle, but there's no reason that wouldn't have happened anyway considering the injuries the staff has suffered.
On the offensive side, I think Lewis' injury was pretty deflating. It was a short stint, but it was quite a good one. If we're talking about expected Opening Day roster guys though, I think it has to be Kirilloff. Between filling in at LF, a very good defensive 1B is missing from this team. That's not a shot at Arraez or Miranda, but neither have the glove Kirilloff does there.
The silver lining of AK's injury is that it allowed Miranda to come up and stay up. That's been a big plus for a lagging lineup.