I think the op is looking for the word performance rather than skill. Skill would be like being able to stop on a bike without puttung a foot down. In skill, a larger rider can be more skilled than a lighter rider with the same age and fitness.

As far as performance goes, then I agree with Red Baron, where an optimal size can be more efficient. This can be overcome. I seen a guy in a Criterium, who was built like a runnung back in football, trying to chase down the leader. This man did not have a typical bike racing body, but finished a 1/4 lap ahead of the peleton, or pack.