were those numbers perhaps cherry-picked to make the situation look more dramatic than it actually is?

If anyone can go from 554th to 5th in any sport/event just by competing among the other sex, nothing else changing, then that obviously indicates something. You can’t handwave that away.

Her personal 100m freestyle time dropping less than a quarter of a second post-transition is honestly a bigger indicator that transition is not making a substantial difference, because that angle completely removes the ‘chance’ element in your opponents being different people.