That is the strongest argument (other than people who actually saw him) for Bradman's preeminence amongst batsmen imo, but I don't think it's impervious to debate. I'm playing devils advocate a bit here, but I think it is conceivable that for a game in it's nascency, where fundamental aspects of it like technique, training protocols, tactics, mental approaches to the game etc. are still very much changing and improving, it would be possible for a single player to rise from the 'pack' easier than in the more professional, modern game. I'm not saying any of these apply to Bradman, but e.g. a player might possess a 'radical' technique that simply works better than what the norm of the day is (and no-one else has caught up), they might have a mental/tactical approach to the game different to other players, they might simply have come up with more effective training methods than anyone else to improve their skills etc etc.. In the modern game, most things are pretty standardized and what works and what doesn't it a lot more set in stone, so I think the odds of an outlier emerging are a lot more slim because it would probably mean they genuinely possess freakish natural attributes (which are extremely rare). IMO, given the immense magnitude of his dominance, Bradman could well have been such a 'freak', but I don't think other explanations should be entirely out of question.