I post on this board while at work (sh, don't tell my boss) so every once in awhile, I may not express something with the thought and care that perhaps I should. But at any rate, I don't mean "instead" in the way you suggest.
Maybe URM and non-URM candidates a separated by more than LSAT. But I think what separates them is pure speculation on anyone's part without seeing the applications. And in the cases when a URM is also socioeconomically disadvantaged, there are likely to be gaps in other areas of the application as well but I would attribute that to $$ rather than race. Which is why I favor socioeconomic AA and not race-based URM AA.