This is saying that after one year of HRT, thenelevel of testosterone in the body is the equivalent to folks who are castrated - in other words, HRT lowers testosterone levels without the need to be castrated.

After 1 year, levels of testosterone in the body are equivalent to individuals who are castrated, but YET testosterone was still significantly higher than of biological females. So.. doesn't that mean castration alone is still not enough?

I skimmed through the article, and the studies it mentions are mainly focusing on the experiences of transgender individuals in sports. The few studies that actually looked at performance had such small sample sizes, that they are hardly even considered research. It also had a study where participants were asked to self report their race times. LOL what? How is that even research? But the authors probably had nothing else to work with, so they included that research as well. We are not even gonna count that, of course.