It makes a great deal of sense that for a yeshiva student, a BTL and LSAT scores would be a poor correlation with anything. Yeshivas (small “Y”) while resembline medieval universities, bare no resemblance to a modern university (yeshivas tend to be collaborative rather than competitive, an emphasis on mastery rather than just getting by with the minimum effort, with much more flexibility and have a greater role of independent work than colleges). It might be worth studying whether most yeshiva students who go to university are either resounding successes or dismal failure (with little in the middle), and what does correlate with making the successful transition.
I suspect one might find a meaningful correlation by looking for transcript evidence of writing ability (since even a brilliant yeshiva student who does well on the LSAT is handicapped since he is trilingual in Yiddish, Hebrew and Brooklynese/Yeshivish but not standard WASPese English even though only the latter is the lingua franca in the legal world) and having a realistic background in the social sciences and American history. However that’s an hypothesis.