Every power rating is just taking high school ratings, maybe portal ratings, production, program history and tinkering with weightings of them with some adjustments for home field, coaches etc
What’s interesting is ESPN produces two power ratings, one somewhat public about how it’s calculated (SP+) and one not. FPI has some blurb about how it runs simulations of games blah blah blah. They bought Connelly/SP+ and put him behind a pay wall until recently for the views but SP+ is clearly not a “ESPN” product with secrecy and motives.
SP+ is most recent update is from the spring, but the most glaring differences are:
Utah -6 by FPI
Washington -5 by FPI
Auburn +4 by FPI
Texas +4 by FPI
Iowa +4 by FPI
Clemson +4 by FPI
SMU +4 by FPI
Indiana is still 6th pre-season, so you could say it’s overweight recruiting rankings now, but clearly it’s not a end all be all otherwise they would be outside the Top 25