They're not the end all be all of rankings. I think for residency, the rankings might get the overall large classes of programs right (e.g., Harvard in the top tier for many specialties) but the granularity isn't there. I guess the USNWR for med school rankings isn't that granular either but for residency, it's probably even less granular than that. The best way to get a sense of tier of program is to talk to residents and attendings. Each program is unique in its own way and it's hard to collapse all of those aspects into a unidimensional measure. For instance, if you care about operative experience, that isn't explicitly measured and isn't obvious until you talk to people who have worked with people coming out of those programs.