CSN Bay Area's Andrew Baggarly sees it playing out like this:
You can lock in most of those 13 position players, too. There's Buster Posey, Hector Sanchez, Brandon Belt, Marco Scutaro, Ryan Theriot, Brandon Crawford, Pablo Sandoval, Joaquin Arias, Gregor Blanco, Angel Pagan and Hunter Pence.
Two spots remain, and Xavier Nady's right-handed bat makes him a fit - especially given the Reds' lefty-laden bullpen. That leaves one more roster spot. Aubrey Huff's success off the bench in September made him a near lock just a week ago, but his lefty bat might not be as useful against the aforementioned Reds bullpen... Justin Christian would be my guess to lead that derby over Emmanuel Burriss and Francisco Peguero.
In the bullpen, San Francisco is looking to keep 12 pitchers, including the likes of George Kontos, Guillermo Mota, Sergio Romo, Javier Lopez, Jeremy Affeldt, Santiago Casilla, Jose Mijares and the five starters. Ryan Vogelsong and Barry Zito are both tough decisions for the Giants rotation wise as Zito could be a dangerous fit against the Reds sturdy lineup while Vogelsong may have made his case over his last few starts (11 scoreless innings in last two outings).
Although the roster hasn't completely been finalized, it would be surprising if any of these guys are left off the roster, aside from Aubrey Huff. Should be interesting what matchups Bochy tries to take advantage off during this series.