Eagles are the Deus Ex Machina of the LOTR universe. They could win things almost automatically, but are reclusive and mysterious, only doing the bare minimum and at the last possible second. It's like the gods are playing a game where they attempt to influence the world without direct force, and try to do shit like sending angels (Gandalf & co) to guide their side, and sometimes responding to prayers in the most dire of times, but despite all their subtle workings they lose every time and have to press the "Send the Eagles" button to salvage a victory, or rely on a completely random element like Gollum.
