And who would that pitcher replace? You've got Doubront and Dempster who are equal to Garza, and Lackey, Buch, and Lester who are all better than Garza.
I'm not sure what the purpose of getting a bottom of the rotation starter would be. Particularly when you've got Aceves, RDLR, Webster, Workman, and Ranaudo who all have the ability to fill in.