Comment by wiml

I would say that a yacht racer, or other athlete's, "output" is their wins/ranking in competitions. There are devils in the details of how you assign a simple number to that, and Goodhart's law is always lying in wait, but that seems to be the right kind of thing to measure.

More cynically, you could measure a racer by the amount of revenue generated by sponsorships, ad placement on the yacht hull, endorsement fees/kickbacks, etc.. If you have two equally competitive racers, but one is more mediagenic, perhaps that one has higher "productivity"? If a racer often loses, but does so in engaging, nailbiting ways that create a following, perhaps that one is "productive"? A wrestling "heel" may lose their bouts but be a successful character, say.