Taken from LSAC:
Correlation is stated as a coefﬁcient for which 1.00 indicates an exact positive correspondence [between the two attributes in question]. A coefﬁcient of zero would indicate nothing more than a coincidental relationship
Correlations between LSAT scores and ﬁrst-year law school grades ranged from .12 to .56 (median is .36). The correlations between UGPA and ﬁrst-year law grades ranged from .09 to .45 (median is .28). However, correlations between LSAT scores combined with undergraduate grade-point averages and ﬁrst-year law school grades ranged from .30 to .62 (median is .48).
If a school has a lower LSAT/GPA median, then it seems more likely that the average student will be less "talented" (for lack of a better word) than the average student at a school with a higher LSAT/GPA median. If that's true, then it seems to me that you would likely be in a higher percentage of the class rank if you went to the school with the lower LSAT/GPA median.
I'm sure I've gone wrong somewhere in my reasoning. Particularly in my interpretation of the data to my premises. I would love to hear why I'm wrong.