but it generally comes down to time. It doesn't sound like you did anything wrong but with an internal temp over 200 it should be very tender. My guess is that it was dry because you were just cooking the flat end. The truth is that it gets all the smoke it needs in those first three hours. At that point you can put it into a foil pan and pour some beef both in the pan then close it up with foil and put it back in for the remainder of its time. That doesn't leave it with as good a bark but the flavor is still there and it will be tender.