Sure, but in the case of a hypothetical AQ, we could do factor analysis and pull out different things, like the strength of various muscles or muscle groups, li

Sure, but in the case of a hypothetical AQ, we could do factor analysis and pull out different things, like the strength of various muscles or muscle groups, like all pure running tests had strong correlation with things like leg muscles. In IQ, this has famously been done and found that a single factor dominates. Or when they saw that knowledge of arcane sport rules interfered, they could look for a more pure test of ability rather than knowledge, which they did with IQ by going from tests of specific factual knowledge to Raven's progressive matrices. And when you do that kind of work, you find that you can develop better measures that have a lot of predictive power for whole populations, even if they do not tell you, say, how many goals they'll score in their next hockey game.