Different Times.

The human army was like a levee while the elven army was like the waters of an ocean. The ocean wanted to overflow and flood the area behind the levee, but the levee stood its ground and didn't budge an inch. 

Again and again, the waters of the ocean crashed against the levee. But again and again, it was beaten back. 

Not that the levee wasn't taking damage. It was as the ocean eroded a little of it every time its waters crashed against the levee. But the levee remained largely intact.

So it was clear that the human army had the upper hand. This is because of their advanced communication system and superior coordination between the living and metal assets on the battlefields. 

This battle is vastly different from the first battle that the humans had against the elves. During that battle, the humans were dropped randomly onto the battlefield.