how have sorority rankings changed over the years?

was set up by National Panhellenic in the mid 2000s to even things out among chapters and create more balance among them by placing more girls. It worked. Chapters that had always been dominant had to release massive numbers of girls before recruitment even started and recruit from a smaller pool of girls. Several traditionally "mid tier" chapters who could carry larger numbers of PNMs moved into the top group and some traditionally "lower tier" chapters moved into the middle. Even chapters that used to struggle are very strong now under this system- in a way there is no longer much of a "bottom tier". The system is still in use in most Panhellenic Greek systems. Top recruiting chapters recruit from a smaller pool of girls; weaker recruiting chapters may invite more girls and sometimes may have more parties.

Also, FYI, at UT RFM also helped make building houses possible because everyone's numbers are stable enough to pay the house mortgages.

With this system many sororities that cut heavy first round do this on legacy or grades and pick from a smaller pool. In doing so they miss nor are open to a huge number of quality girls before even getting to know them. Stay open minded because all sororities matter at UT. You will find more diversity in some of the chapters that invite you back at least. Couple rounds. They are truly wanting to get you for you verses a form

But remember, those sororities do not cut heavily because they want to. RFM gives them a number they must meet. So grades, recs, etc. are really the only things they have to go on. This works to the advantage of chapters who don't have to cut as many, as it is supposed to - thus the movement in tiers over the past few years.
All chapters are good at UT, so it works out in the end for PNMs maximize their options.