I’m not entirely convinced by ratings based on average times.
Taking Trirating example, imo the field at Wales is almost entirely dominated by proximity. Whereas the field at Lanza is dominated by people who really want to suffer and can afford the flights. I did Lanzarote and Switzerland in 2019, trirating has the swim 2 mins faster at Lanzarote, but in real time I swam 3 mins faster at Switzerland. It’s not feasible that I became a 5min faster swimmer in two months. I’m not saying it’s wrong but maybe it’s the wrong measure on it’s own.