Begin by mixing the dry rub together & rubbing it on making sure to thoroughly cover the meat. Then let it sit for 1-2 hours while you get your smoker up to 225F.
For the mop start by mixing everything besides the mustard, butter & garlic together in a bowl to the side. Then melt the butter & add the garlic for 2 minutes. Add the bowl you set aside earlier to the sauce pan & just let it cook for 15-20 minutes over low/ medium heat. Lastly mix in the mustard while its still warm and let it set for 20 minutes.
Place the roast on the smoker using the mop marinade every 45-60 minutes to help ensure flavor & moisture in the meat.
Pull off the smoker after about 4 hours. The meat should be a temperature of 145-155 while its still medium rare. If cooked to well done this cut of meat will be dry no matter what you do to it.
