Earlier I asked you how much fat you leave on. I think even though Aaron Franklin recommends leaving a layer of soft fat on the brisket and I was also taught that in a BBQ class I took, I just read that the fat cap doesn't do a thing to retain moisture in the meat. What appears to be an important factor in turning out a most, smoky brisket is letting it rest wrapped or underneath a towel inside an insulated cooler for an hour or two. While I like to finish the brisket unwrapped I like to wrap it in foil before placing it inside the cooler. With the next brisket I think I might wrap it in butcher paper with foil around it before it goes inside the cooler. Allowing it to rest enables the meat to reabsorb fat and juices and that's how to virtually ensure a moist, smoky brisket.
An undercooked brisket can be less juicy and moist than a perfectly cooked one since not all the fat has rendered. I still think that's what helps make the meat moist despite the two articles I read which state the contrary.