Age + current contract. The two things Belliard can't control are the top two reasons Felipe will probably start next year. Lopez is 26, Ronnie is 33. Felipe has a lucrative deal right now, and is considered a building block for the franchise. As much as Ronnie has outplayed Felipe, it's a very complicated choice.
Lucrative deal? Felipe isn't even signed for next year. Belliard is signed until 2010.