I would not say MUD is usually a bye (I have lost to it even maindecking 4 ancient tomb, 3 viashinos, 3 welders, bolts, gorilla shamans, ssg...), but after sideboard is pretty winnable.
Would ancient tomb deserve a try? 4 Ringleader, 1 commander, 1 kiki jiki, 1 sharpshooter, 4 matron, 1 krenko, 4 earwig, 4 chalices, 3 null rod. those are 23 cards that would directly benefit from having ancient tomb. Goblins is more mana intensive than it seems, look at the average!
I maybe miss some removal, and perhaps sulfur elemental, but are just ideas and I should play the deck to have a clear idea. Anyway the deck looks pretty solid
