Yep - I see what you mean. There is a positioning tab on the back of the derailleur in the drop out though, so as long as the axle bolt is tight it should keep working, no? I expect the adjustments would be all out of whack again though when next the wheel comes off.

Still, I did improve the situation - the derailleur was on the wrong side of the drop out tab and rotated forward so that it was binding on the frame when I got it. It only had 2 or 3 gears of movement when I got it.