That saddle is likely flexible enough that you're sitting in a shallow trough that is effectively level where your weight is centered. That's why riders can often get away with using a saddle that's tilted down a couple of degrees.

The less flexible the saddle, the closer to level the saddle will be, assuming that the rider does enough mileage for the bike fit to matter. I can't recall seeing any pictures of pro riders with their saddles set more than a degree or two away from dead level, if at all.