The main factor behind the apparent unstoppable success had by the Redstonian forces during the great Grief was there only due to their mastery of tyranny, and it's effective deployment as a weapon of war.
Tyranny however, is a force one cannot simply obtain and then forever wield, it only takes so many quick and easy victories before the wielder takes such comfort in its strength that it's true essence begins to fade.
Just as the balance of power shifts overtime, The time for another to wield that power has now arrived in the east, and this time it's power shall not simply decay overtime. As for once it's not in the hands of a single man, but in the hands of a unified collective.
-Borous Von Dragestein, During the opening of the Fourth Era