The current standard, called “the Stockholm consensus,” involves that the transexual must have sex altering surgery AND hormone treatment sufficient to remove the advantage that men have relative to women in many sports. Admittedly, the second criterion involves an arbitrary cut-off point along a continuum.
One of the way stations in this evolution was the “female at birth” criterion. This rule didn’t work so well as there are some persons who actually are “intersex” at birth (quite rare). There also are others whose genetics and hormones are clearly male or female at birth but whose self-image is or becomes the other way, whom the majority in society want to accommodate.
I myself think the “female at birth” criterion combined with the Stockholm rules for those very few people people who actually are intersex would be sufficient in sports where men have a natural advantage over women.
I think the way I would accommodate transexuals in sports in which men have an advantage, is to have them compete with the males.
No matter how mutilated he’s made his body, or disabled by unnatural hormones, this man has the advantage of larger bones and muscles formed by male anatomy.
This is significantly unfair to the real females—esp. on other teams or his own.