Here's a map of the zone:
Here are my arguments:
The Horde base's side exit is a water tunnel, making it very slow going for any Alliance flag carriers.
The Alliance base is on a cliff, allowing the Horde to jump off with movement speed + parachutes allowing for a flying flag carrier to get all the way to, if not past the river very quickly and safely.
What do you think? Personally, I can't get past seeing a Goblin Mage fly to the river and then rocket boost across the river. Having a Sprint would make it all the more ridiculous.