Maybe someone can help me here, I can't figure out how drks are using more tp than a pld while tanking? I can see a tiny difference while off tanking because of blood weapon increasing speed. Even then when a pld runs out they can't do any damage besides AA and circle of scorn on cooldown.

If anything I'd argue that while tanking they have better tp management than pld. Shield swipe is 40 tp and a dps loss. It also can't be used while not tanking. Unmend, while less potency, is 0 tp, which would get you back enough usable tp faster than a pld doing shield swipe.