Mid-tier or not is a judgement call.
Regardless, Lia went from not being in the front of the pack, to being in the front of the pack:
“By the conclusion of Thomas's swimming career at UPenn in 2022, her rank had moved from 65th on the men's team to 1st on the women's team in the 500-yard freestyle, and 554th on the men's team to fifth on the women's team in the 200-yard freestyle.”
65th to 1st in one category, and 554th to 5th in another.
It is fair to say there was a significant increase in rank post-transition.