rosales graduated from reseda high school in 1999. rosales attended california state university, northridge and was drafted by the san diego padres in the 20th round (581st overall) of the 2003 major league baseball draft. he spent 4½ seasons in the padres system. on july 27, , he was acquired by the arizona diamondbacks for outfielder scott hairston. he had been out with a right hand injury since june 5, 2007, when the arizona diamondbacks acquired him.