No way was she a pushover. But tackled from behind, where the predator knows what is going on but the prey doesn't, the predator has advantage. Especially a predator that outweighs you by fifty to a hundred pounds, has more muscle, not to mention a weapon, as well as having the drop on you.
On top of this advantage, If he followed his mo and knocked her into the ravine like the other woman, she might have been injured and completely lost her chance to escape. Or, since this was a first for mr G at this location, he never relaxed and gave her a chance to escape.
His last victim was not only savvy, but also LUCKY. She had an opportunity to try to escape.
As far as the map, etc. I think she went to the park with a destination. In fact, I think she met up with Condit that afternoon.
It's not yet established that the body was found in a ravine -- there's been some suggestion (on this thread and elsewhere) that it was found at a higher elevation than the jogging path. According to the DC police chief, it was far removed from the path, near "rocky cliffs," and "rough terrain."