^I suspect it's Cav's short legs that allow him to sprint with power while keeping his upper body so low. Other guys have to extend longer legs and thus move their bodies up. That's my armchair analysis.

Cav simply has a jump that no one else can match, which gives him a huge opening gap. The aero position allows him to maintain his top speed without having to sustain giant wattage, which is something a short-sprinter like him can't do. Simply put, he was born to sprint on a bicycle.