I haven't seen data for how new registrants voted in 2004 crosstabulated for who sought to ensure they were registered.  But as I understand it, the Obama ground game is targeting persuadable and unlikely but supportive voters and registering them. They are not  approaching, persuading, or registering people who have no propensity to vote for them based on a variety of indicators determined empirically in advance. See here for long, verbose, and wonky details

Index of Frank's Diaries