In a small bowl, mix all of the rub ingredients. Massage all over the brisket. If you can allow your brisket to marinate for 24 hours this will bring out the most flavor.
Combine the bbq sauce and stock in a bowl. Place carrots and potatoes on the bottom of the slow cooker. Then add the brisket, fat side up. Pour bbq sauce and stock on top.
Cook brisket on low for 8-10 hours. You want the internal temperature to reach 175ºF.
After it reaches the desired temperature, remove and allow to rest for 10-20 minutes before slicing.