OBP Error

How is it possible to have a better BA than OBP?
Juan Pierre is batting .321 but his OBP is .300
http://fantasygames.sportingnews.com/stratomatic/team/team_other.html?user_id=79094
Juan Pierre is batting .321 but his OBP is .300
http://fantasygames.sportingnews.com/stratomatic/team/team_other.html?user_id=79094