Is a tough brisket due mainly to the meat itself? We followed what seems to be a standard recipe, cooked a 4 1/2 lb brisket at 200F for 4 hours over smoke, then wrapped in foil and cooked to 140F internal. Pulled out of the box, wrapped in a towel and stick it in a cooler for about 45 mins. End product was tough. Flavor was good, but I was seriously unimpressed by the results of my first brisket. Some background info... meat was bought from a major chain store, had about 1/4" fat cap (not entire cut was covered). Stuffed garlic cloves into meat night before. Applied a rub about 1 hour before cooking. Mopped meat every 1 1/2 hours. Smoked over hickory chips (electric smoker). Made sure water pan was holding for the whole smoke. I'd really like to understand where I went wrong. I don't think I did anything goofy, so that leaves the meat itself (unless someone can show me the error of my ways). So, then, how do I pick a better chunk of meat next time?