I suppose it would have to boil down to that. It just seems a little odd to have both attacks trigger on a normal attack, but not a sneak attack, and to also have a separate ability to attack with specifically the off-hand. Plus the sneak attack tooltip appears to say there's only a 1d6 added, but at the same time it's evident in the combat log that there's some sort of formula calculating damage in addition to that die roll. It's all very confusing.
Nevertheless, I'm still enjoying the game for what it is so far.