I don't really worry about backups as I am confident that, at least early in the year, there will be guys available to trade. I did end up with some though but am mostly more trying to get the best guy available.
With your lineup though, you may want to try a backup catcher. That's a good position to have a backup if you can figure out how the 'rotation' works and when Pudge will be getting a break and all of that.
My team is: Ramirez, Soriano, Sheffield, Sexson, Vazquez, Foulke, G. Anderson, C. Lee, Berroa, Zambrano, Livan Hernandez, D. Young, Santana, Contreras, Donnelly, Ensberg, R. Hernandez, Worrell, A. Benitez, A. Sanchez, Jason Phillips, Crosby, Riske