If the question is crispy skin, these related questions (1 and 2) provide a lot of tips and tricks to get what you want. As you can see in this answer, the trick is to start at a lower temperature to render all the fat - you also want your chicken sitting on a rack or on top of vegetables so it's not sitting in the fat once it's rendered. Towards the end of your cooking you want to turn up the heat to crisp up the skin after the fat has rendered.
Note that watery meat isn't good, but you do want to keep your meat moist, so you don't want to cook it so long at a high heat that it dries out. Tender meat is greatly helped by using a brine.
I suspect you may have created a poor-man's slow-cooking environment in there. You had meat, and liquid, and a median temperature of around 200° F, and you probably also got the bird close to "done" during the first broil, before you even left the house. This is obviously easier to do when the meat is covered (was it in a covered roasting pan?) due to the steam, but the oven does provide some insulation to begin with.
Technically when slow-cooking you should theoretically be able to speed up the process by quickly bringing the meat up to just below doneness/moisture-loss temperature (130° F) and then switching to a moisture-preserving slow-cook method like braising. I think that's what you accidentally did, but it's hard to say for because nobody was there for an hour and it sounds like you didn't check the temperature before the second round in the oven.
My guess is that the second roast at 400° F was probably unnecessary, and that the bird was already done, having been cooked in a very slow roast.
I'm pretty sure it wasn't the basting that helped. It seems to be regarded as a myth these days that basting keeps the meat moist, because the baste really doesn't penetrate the skin (and it's not the skin you're worried about). Basting is done to add flavour, not preserve moisture.
The recipe itself also doesn't strike me as anything special in terms of keeping the bird moist, aside from having a relatively short cooking time (as with any grilling/broiling) and letting the meat rest afterward, neither of which really apply in your case. It was probably the slow heat that did it.
Best Answer
I use a fairly high heat of 500F (260C) to render fat and crisp skin (after chicken has been air drying in the refrigerator overnight). Most of the time, for me, a whole chicken takes about an hour and 15 minutes. Depending on size, a spatchcocked bird will take about an hour. Use a thermometer to gauge your preferred doneness.