I’m afraid that is following the concept through. Part of what Michael Cox explicitly stated is that the top footballers are better at their sport than Bolt/Jordan/Dan Carter etc are at theirs. And his reasoning for that is that more people play football, so it is harder to get to the top. But if you follow that logic to its natural conclusion, any Ballon D’Or winner (for example) should be better than any basketball MVP or heavyweight champion or whatever because millions more people play football than do those other sports. Hence my Sammer v Jordan example. It’s just not that simple.
Saying that it’s harder to get to the top in English football than Welsh football is not relevant because it’s the same sport with similar structures and similar things you have to do to get to the top, with England just having more people and more resources, so even the best Welsh footballers (who can often be better than the best English footballers) move to England.
Comparing it across sport like Cox did is totally different because the obstacles are different and the amount and type of work is different in each case. It’s like comparing a race against 10 other people where all you have to do is run vs a race against only 5 people but you have to swim, fight off alligators and climb mountains. Just because you’re racing against less people, it doesn’t automatically make it easier.
Moreover, football is not an exact meritocracy, the people at the top are not always the best people. It’s probably more of a meritocracy than your average profession for example but there‘s still connections, nepotism, networks etc that influence who ‘makes it’ to the top level and who doesn’t.