Does affirmative action in education help its supposed beneficiaries?

As this post over at The Volokh Conspiracy says, linking to an article by Gail Heriot, that research indicates that affirmative action actually harms those it is intended to help: The Sad Irony of Affirmative Action. The problem of mis-match appears to be a very real one, and it is the mis-match between the ability of students benefitting from affirmative action with the academic requirements of the educational institutions they are attending is the key factor which leads to harm.