The charts they posted show the highest playable settings, them the post am apples to apples.
More food for thought. Why did we all wait for bf3 benchmarks? We post benchmarks ALL the time that's taken from pure gameplay. Some benchmarks are even from multiplayer!
Taking a random 5 second interval of gameplay and saying that's the benchmark would be questionable because it could be the outlier. But they did 7-8 minutes!