SAN FRANCISCO -- The Giants' roster could continue to evolve throughout Spring Training and into the start of the regular season.
Executive vice president of baseball operations Brian Sabean and general manager Bobby Evans indicated Friday that the club is continuing to search for upgrades in the bullpen and outfield.
The Giants would like to add a proven reliever, even after signing left-hander Derek Holland to a Minor League contract on Friday.
"The 'pen still could be a work in progress," Sabean said.
Management has not committed to naming free-agent acquisition Austin Jackson as the everyday center fielder. The ballclub is still leaving open the possibility of making another acquisition or watching rookie Steven Duggar establish himself as the Opening Day center fielder.
Jackson, who signed a two-year, $6 million deal, said that he'll be ready to fill any role the Giants assign him, whether he's the everyday center fielder, a platoon center fielder or a backup at all three outfield spots.
"They were very upfront with what they'd expect of me," said Jackson, the right-handed-hitting half of a center-field platoon last year in Cleveland.
• Right fielder Andrew McCutchen sounded thrilled to have the opportunity to wear the Giants' home uniform. It's a matter of tint.

"That was something I always said, that the cream [color] on the uniforms is so nice, as opposed to the stark white. That's awesome," said McCutchen, who spent his nine previous big league seasons with the Pittsburgh Pirates.
• McCutchen also revealed, contrary to popular belief, that his son, Steel, did not derive his name from the material that made Pittsburgh famous. McCutchen explained that he and his wife wanted a "strong" name for their offspring.