Let's compare the two MB's the Cubs acquired the past two years.
The 2009 MB, Milton Bradley.
Here is Bradley's April, 2009 line:
4 for 34, for a .118 average, 2 HRs, 2 RBIs. And Cubs fans booed Milton.
And the 2010 MB, Marlon Byrd:
This April, he was 31 for 93, for a .348 average, 4 HRs, 16 RBIs. Byrd is quickly becoming a Wrigley favorite.
Sorry Milton, but it wasn't the color of your skin that brought out the negative fan reaction. It was your performance on the field, or actually, your lack of performance. Admittedly, the fans may have been impatient. But you didn't play well and you heard about it. Marlon is playing well and he is hearing about it too.
Cubs fans don't care if you are black, white, green, or purple. Heck, they even cheered for long-time Cardinal Jim Edmonds when he came to the Cubs. All they care about is winning. Help the team win, and you will hear about it. Contribute to the team losing and you will hear it, too.