I'm not quite sure of why a defensive CAP 3 would be much better served as a physical attacker than as a special attacker. As a defensive Pokémon, it's already benefiting from not suffering from the HP leak from a burn. The Attack drop prevention is cool but I don't think it's all that substantial, again assuming a defensive CAP 3 for the sake of argument. For a specially offensive defensive CAP 3, however, Fire has the advantage of having a reasonably accurate, no-recoil 120 base power STAB, as well as an 80 base power STAB that can burn rather easily, both of which many other types do not have, and only Water comes close to having together. The former is a very concrete advantage that other types would need much higher stats to pull off. As a side remark to srk, yes, our concept is typing makeover. It's not Break the Mold.