According to the CHONE, Marcel, and Bill James 2009 projections, the difference at the plate over a full season between Bobby Abreu and Reggie Willits is about 20 runs.
According to UZR, +/-, and Revised Zone Rating, the difference in an outfield corner over a full season between Bobby Abreu and Reggie Willits is about 15-20 runs in the other direction.
Should the Angels go on to sign Abreu as expected, they'll be improving their team for little commitment, but it's hard to feel like this whole OF/DH situation of theirs couldn't have been handled a little better. At this point, especially with that outfield, I think I'd rather have Willits than Juan Rivera.
Mike Scioscia is going to have a complicated season.