Does Letter Quality Correlate with Pedigree?

As a weird coincidence, these two comments showed up overnight, making the same interesting point:

As someone who has chaired a number of SCs at a highly competitive SLAC, [snip] For all the righteous indignation about the role pedigree plays in hiring decisions, I will say that the letters from faculty at more highly ranked institutions are, as a whole, an order of magnitude better than those from less selective places. The level of detail, engagement with, and subtle assessment of an applicant's work and potential is--by and large--much more impressive when the letter writer is from a top place, and I think that plays far greater a role in hiring decisions than many people acknowledge. It's not just the aura of the Leiter rankings--it's also the quality of the letter that come from the more esteemed departments. This disparity in the nature of rec letters is likely unfair to those very smart people applying from programs lower down the food chain, but I think it's worth noting in the context of complaints about how pedigree exercises an undue influence in the application process: one additional advantage to being at a higher ranked program is the strength of the endorsement letter you receive from your recommenders.

This might be a tangential remark, but in the context of various complaints about the role that pedigree plays in the hiring process--an admittedly fractious issue--I wanted to note that there is a high correspondence between the rank of a department and the quality of the letters from an applicant's recommenders (I speak as someone who has chaired three searches in the last five years). It's not just the reputation of the institution an applicant comes from--it's also the level of detail about, engagement with, and subtle assessment of an applicant's work that comes from a highly ranked department's letter writers. Given the importance of recommendations in the application process, it's important, I think, to keep this in mind when raising complaints about the supposedly undue influence pedigree plays in hiring: it's not just the aura of the letter writers, but the informativeness of the letters themselves, that plays a key role in why applicants from better-ranked places do better on the job market than those from less prestigious places