Assuming Marchand (52kg) rode a UCI weight limit bike (6.8kg), and assuming he rode on the hoods for the whole hour (the position shown in the photos), and keeping all other assumptions default, his 14mph ride required about 69W of power.
With the optimized aero bars setting, which is approximately the best aerodynamics possible using the relaxed post-2014 rules, the same power allows a speed of 15.15mph. Not quite 10% improvement but not far off.
Yes but it's worth noting that for a person of any age it's harder to generate the same power in a fully aero position because you are choking the engine!
In my experience, the tucked TT position is just as much about generating power as it is being aero. Granted time trials aren't my strongest event when bike racing, being in an aggressive position seated far more forward on the saddle allows me to generate more down force – at least it feels that way. In two similar events a few years ago I went from ~24mph to ~26mph by just adding aero bars to my road bike, and further improvements when I got a full TT bike. I know there are a lot of factors (wind, road conditions, etc.), but sitting in the aero bars really feel far more powerful than sitting upright on the hoods or even in the drops.
Assuming Marchand (52kg) rode a UCI weight limit bike (6.8kg), and assuming he rode on the hoods for the whole hour (the position shown in the photos), and keeping all other assumptions default, his 14mph ride required about 69W of power.
With the optimized aero bars setting, which is approximately the best aerodynamics possible using the relaxed post-2014 rules, the same power allows a speed of 15.15mph. Not quite 10% improvement but not far off.