I can confirm this as well. My group was never able to pinpoint if it was damage as a whole (which I doubt), or if certain damage types boosted certain TP moves. This was testing done near release, so no logs still remain to my knowledge. If you spam Dia1 you do almost nothing, and you'll notice his moves (can't remember if all, we had a pld holding it though so physical moves would be skewed with ochain) do significantly less.