Why is Luge Faster than Skeleton?

Sled runners and aerodynamics:

Why is luge faster than skeleton? Two main reasons. First, it has to do with the materials of the respective runners, or the metallic bars attached to the underside of the sled. Skeleton racers ride downhill atop a set of tubular steel runners, which sort of look like they were yanked off of a stainless steel towel rack. The dullness of these runners helps to limit a skeleton racer’s speed. A luge sled, by contrast, rests atop a pair of razor-sharp steel blades that cut into the ice like a pair of skates. The sharp edges of the luge runners help make the luge sleds faster than their skeleton counterparts.

Another reason why luge is faster than skeleton? Luge racers assume a much more aerodynamic position than skeleton racers. In skeleton, you lie face-first on the sled and lead with your helmet. In case you haven’t seen one lately, helmets tend to be big and round. All of that surface area creates more drag, slowing the skeleton sled down. But luge racers lie on their backs and lead with their feet. Less surface area, less drag, faster sled. It’s basic science, people!

I guessed the aerodynamics, but I didn't realize the skeleton sleds used tubular runners.