Profs. Volokh and Kerr offer some thoughts on mean law school grades across the top 20 or so schools, but the discussions are "excluding schools like Chicago and Yale that have their own grading systems." Well let's throw Boalt on top of that too.
In my first ever post at De Novo I noted that one of the benefits of our obscure grading system is that we can't really compare with our classmates too easily so we just don't. I'm glad to see my point reinforced on the macro level as well. (A) I'm not at all shocked that legal education has an underlying need for comparision with "peer" schools about even such trivial things as grading and (B) I'm glad our awkward grading system keeps us away from the market pressures.