Much like what #Gugie said above. The spokes under the most tension are the pulling spokes on the rear hub. Since most spoke failures occur at the bend, a pulling spoke should be on the inside of the flange with the head facing out. This gives the spoke a slightly straighter pull angle at the bend when the wheel is under torque. If it were laced to the outside it would then also have to bend around the outside of the flange at a greater angle which could increase any weakness. Having said that, spokes these days are of such excellent quality that it really does matter that much. Breaking a spoke on a properly built wheel under normal riding conditions is quite rare without some outside influence. Just my opinion though and worth what you paid for it.