It would however be reasonable to conclude that the author does not have strong analytic understanding of what exactly makes them a strong player/​good writer, and be cautious about the more abstract parts of the advice, similar to how native speakers can tell you whether a sentence is grammatical, but are usually less reliable for giving you general rules than speakers who learned the language as adults to a high level of proficiency.
It would however be reasonable to conclude that the author does not have strong analytic understanding of what exactly makes them a strong player/​good writer, and be cautious about the more abstract parts of the advice, similar to how native speakers can tell you whether a sentence is grammatical, but are usually less reliable for giving you general rules than speakers who learned the language as adults to a high level of proficiency.