Trivia: they've hired someone to design a really clever chess puzzle for the movie that fits the description from the books (you have to find a hard move that results in checkmate without losing Harry and Hermione but by sacrificing Ron), then the director of the movie totally messed it up and you can't even see the position in the film.
I also don't buy that Ron is that good at chess. I think Rowling models chess as a total unitary property: doesn't say anything about the person. But that's most likely not true.
I have admittedly heavily updated downward on how closely dominion is linked to IQ over the years, and chess would be kinda similar. (It's also trivial to see that the link can't be too strong because they're not that correlated to each other, e.g. I'm way more talented at dominion than chess.) But (a) there is certainly still some correlation, and (b) even though they are both a poor measure of IQ, they probably still measure something. I kind of buy that just about any type of person can be a world class player in things like football or tennis (I think this is born out by examples); I don't buy that this is true for chess or dominion. It's just poorly understood what exactly the requirements/correlations are. But for example, my impression from hearing top chess/primsata/dominion players talk is that they are altogether much smarter (using that as a name for overall sanity level, not IQ) than the average person, and that doesn't seem particularly true for say football (meaning soccer).
Point being, based on my intuition about what this link is, Ron isn't the kind of person who would be good at chess. Even if I'm unsure about the characteristics, he doesn't seem to check any of the boxes.
It could have less to do with talent and more with being the kind of person who is willing to grind by themselves. That theory would predict that the dividing line could be solo vs. team sport rather than phyiscal vs. mental, e.g. dota could be a little more like football.
Or maybe all of this is BS; much more uncertain about all the above than most things I talk about.