At least I thought so. http://www.ble.state.tx.us/one/analysis_0704tbe.htm#q4 Apparently there's a CLOSE connection between the LSAT and Bar pass rates, herd copy study material works better than Internet study, lots of other good stuff.
So the results of a standardized law entrance exam appear to be correlated with the results of a standardized law exit exam. Seems reasonable enough. You could do the same analysis for standardized medical entrance exams (MCAT) vs. standardized medical exit exams (USMLE, COMLEX). In fact, it's been done already, with similar results.
I wish there was a way to test whether the LSAT could predict competence as a LAWYER. The ABA stranglehold might not survive...