I don;t believe its SKILLS that yields this impression (if indeed that impression is there). Rather its efficiency in size rergarding physics.
As an engineer, I have read literature that indicates Size is optimized due to physics of movement (moment of Inertia mostly). We all know big tall folks are 'gangly' while short thin folks are 'quick on thier feet'. In some military literature I read on extreme ranger school exercises, it was pointed out that 5'9 +/- (assumption was that skills, fitness, etc was equal) was the optimium size efficiency.
Perhaps 'junk' but interesting.