I looked at California, which has eighteen ABA-accredited schools (and therefore a lot of easily accessible data thanks to US News) and ran a few correlations. The correlations of bar pass rate and US News peer assessment, lawyer/judge assessment, 25th percentile gpa, 75th percentile gpa, 25th percentile LSAT, 75th percentile LSAT, LSAT midpoint, percent of applicants accepted, and student/faculty ratio are in the table below.
Some things jump out: like how highly bar pass rate is correlated with perceived quality (as measured by peer assessment) and law student quality. None of this is surprising, but it suggests again that US News peer assessments are measuring essentially the same thing as student quality, which in turn measures essentially the same thing as bar pass rates. How all this relates to the quality of output, I am unsure. But it makes more understandable law schools' focus on LSAT--particularly if they are concerned, as they seem to be, about their bar pass rates.
The plot below illustrates the correlation between bar pass rate and LSAT mid-point of a school's students, for California law schools.
Alfred L. Brophy