Just going to be a douche and say complete BS.
The amount of XP gained is nowhere near the 10 mil XP you need to get 99 smithing. The BEW last for 3 days or 72 hours or was it 4 days (96 hours). Anyways, let's just give you a HUGE leeway by making XP X2 for the first 10 hours. Assuming you will be smithing mithril plates since minigame xps, SC hammers will not work. You'll get 70k/hr (with the multiplier). meaning, 700k xp for the first 10 hrs. The remainder of the time, you'll be receiving ~40k/hr or 2.4KK xp for the 62 hours. Your nowhere near lvl 99. You'll get level 85 smithing, i believe?