Less than half of the Giants’ current roster remains from the team that won the World Series in 2010. There are only 11 holdovers, or 12 if you include Game 1 starter Barry Zito despite his not being on the actual playoff roster in 2010.
Carl Steward of the San Jose Mercury News has the full breakdown, with the biggest additions since 2010 being Ryan Vogelsong, Hunter Pence, Angel Pagan, Brandon Belt, Brandon Crawford, and of course NLCS MVP Marco Scutaro.
Meanwhile, the Tigers actually have three holdovers from the 2006 team that lost in the World Series to the Cardinals: Justin Verlander, Ramon Santiago, and Omar Infante, who left and played for two other teams before coming back in the middle of this season.