A choice brisket may require wrapping, paper or foil. It sounds like bark was very hard, so again, wrapping might be of benefit. Just to verify, were you slicing across the grain? The next brisket you cook, just try changing one or two things, so if you fix it, you'll know what you did. Is prime beef an option? If so, I recommend it. If not, definitely give wrapping a try, and up the temp, everything else looks good to me. Rob