Wrong. You need 71% Eclipse bonus, which translates to 41% Mastery. In Moonkin, we already have 25% mastery without any gear. 41% Mastery isn't all that much.
It's also not unreasonable to assume that Blizzard intends to tune Mastery to be better than Haste once they actually get to that development stage, since the intended stat priority for all classes is primary > attuned secondary > other secondaries.