My opinion is the choice brisket was just not as moist as the prime briskets I have cooked in the last year. The brisket had been frozen for almost a year and when it was thawed out I poured out a lot of liquid from the package it was in, which may have contributed to lack of moistness also. I have always trimmed my briskets the same and cooked choice and wrapped in foil before and always been happy with tenderness, flavor, bark and moistness. All briskets are just not the same. I`m still not sold on the pink butcher paper method and will go back with my foil. Lots of great BBQ place in Texas still using the foil method and have been for years. I didn`t cook the whole brisket till 210 degrees. The middle of the flat was 205 when I pulled and the point was 210. I pull it off when it is probe tender and not by temp anyway. Some briskets I have pulled at 200 and it was done.
That’s a common misconception. Most dry briskets are undercooked. It doesn’t sound like yours was but that is the usual culprit. When you cook a steak the myoglobin and other moisture is what is “juicy”. Myoglobin is the red liquid that people usually confuse with blood. When you cook a well done steak the proteins squeeze a lot of this moisture out of the steak which is why it’s dry.
Briskets do this too. We just cook past that point. A brisket with an internal temp of 175 is dry as a bone. The long cook relaxes the proteins which causes tenderness, but you can’t replace the liquid. When you get a hot enough internal temperature the marbled fat starts to render out which takes quite a bit of time that marbled fat is where the juiciness comes from. It takes hours to render. That’s why people say probe tender instead of temperature. If you cook at 275 and have little marbled fat your brisket may be probe tender at 200 degrees. If you cook at 225 and have a lot of fat it may be 212 degrees. This is also why people say to rest for hours in an ice chest. It keeps the temperature high enough to render fat but doesn’t cook the brisket anymore.
Remember wrapping wasn’t intended to give you a juicier brisket. It was to help push your brisket through the stall at about 160 degrees. I’ve had plenty of never wrapped briskets that were excellent. But I don’t like a four hour stall. Each wrapping method will produce a different brisket.
If I had to guess, and it’s only a guess, I would say the freezer was your culprit. Fat doesn’t freeze well for more than a few months. I would suspect some of the fat hardened up and wouldn’t render during cooking which is why it came out a tad dry.