Does affirmative action lead to unprepared students getting into college?

Many defenders of affirmative action claim that it “levels the playing field” but if it leads to students being accepted who do not meet the rigorous standards, they may not be successful in college and will be more likely to drop out. How does this benefit underrepresented minorities in the long run?

Stanford University seems to have acknowledged this issue to a degree by creating a special physics course that provides extra help to minority students who may not have had adequate preparation for a college-level physics course in high school. These students were admitted to Stanford but don’t have adequate preparation for a normal Stanford physics course? That seems to indicate that indeed, affirmative action is allowing students in who do not meet academic standards but are the right race.

Obviously more needs to be done to improve schools so minority students are adequately prepared. But in the meantime, should there be more minority-exclusive courses in colleges designed to provide a leg up?

My 200th question :D