Not sure about ranking but if you watch idol school you can tell how far they have come in terms of vocals, dancing and performance. The girls would be crying and become frustrated because it was really 2 months of boot camp for them.
After idol school, Fromis' room showed the training they went thru on a daily from singing/dancing to exercise and to putting their names out there.
If I ever did a ranking on the members in terms of improvements would say Jiwon, Hayoung, Gyuri, Seoyeon, Nagyung, Chaeyoung, Jisun, Saerom, Jiheon.
This latest comeback album really showed the world their vocals and I'm happy they did. They all sound amazing and deserve some praise.
