I can't find a reasonable way to justify this move... if you're trying to win more games, you've got to put him in your lineup every day no matter the position. It would make more sense if there were an actual log jam, but with Miranda looking completely lost at the plate, I don't get how he's still here. If anybody needs to get back to AAA ASAP, it's him. And if it's because we need a backup 1B - suddenly why do we not care about Miranda's development and only Lewis'?
I would consider DFA'ing Nick Gordon, he's a .600 OPS hitter when we've already got Celestino and Garlick on the bench (once Larnach is healthy), with his main strengths being speed and hitting singles. Very poor OBP, little power, not a big threat to steal bases, can't hit at all versus lefties... with Contreras as a fine backup on the 40 man, I'm not sure if Gordon is needed anymore.