Season the meat: In a small bowl, mix together the brown sugar, smoked paprika, garlic powder, onion powder, salt, and black pepper. Rub the seasoning blend evenly all over the beef brisket.
Sear (optional): Heat the olive oil in a large skillet over medium-high heat. Sear the brisket for 3 to 4 minutes on each side until nicely browned, then transfer it to your slow cooker.
Mix the liquid: In a measuring cup, whisk together the barbecue sauce, beef broth, and Worcestershire sauce. Pour the mixture over and around the brisket in the slow cooker.
Slow cook: Cover and cook on LOW for 8 to 10 hours (or on HIGH for 5 to 6 hours), or until the brisket is fork-tender.
Slice and serve: Remove the brisket from the slow cooker and let it rest for 10 minutes. Slice thinly against the grain, and serve drizzled with the leftover juices and extra barbecue sauce.