I go bonkers when I read about various ways to keep meat moist, like marinades, water pans, mops, sprays, etc. Water, in the meat, is bound up in the protein strands. When a protein is overheated it has no choice but to release that water, by that same account anything you do to the meat isn't really going to add to that water that the protein is wrapped around. Meat boiled in water can easily dry out, so why would a water pan be inherently better than that? Imagine cooking a soaked sponge, as it warms it slowly contracts, over a certain temp it wrings itself out completely. Would a slightly more humid cooking environment stop this from happen? Would spraying a bit of apple juice on it help?