Any school ranking that is heavily weighted by number or per capita numbers of Rhodes scholarships will probably tell us more about the strength of the schools’ scholarship prep programs than about their actual academic strength.
Some colleges take the Rhodes very seriously and have committees, advisers, and coaches that identify and groom potential candidates from early in their college careers - helping them build portfolios of achievements and drilling them to prepare for the interviews. Other colleges either don’t have the will or the money to spend on this sort of prep and give it short shrift. Any students who win a Rhodes from those schools do it all on their own.
Thus the numbers of Rhodes winners coming out of any given schools can be heavily biased based on their institutional focus on winning lots of Rhodes. An example of schools that do put tremendous effort into their Rhodes programs are the US service academies.