SAN FRANCISCO -- Stability, on the field and off, explained Jeremy Affeldt's decision to remain a Giant.

Seeking a multiyear contract and cherishing a World Series-winning roster that should stay mostly intact, Affeldt signed a three-year, $18 million deal. The agreement was officially announced Wednesday, though it was initially reported late last weekend.

Affeldt's accord left second baseman Marco Scutaro and center fielder Angel Pagan as San Francisco's top unsigned free agents. Responding to a question in a text message, general manager Brian Sabean described the status of negotiations with both players as "ongoing and upbeat."

As a free agent who happens to be a valuable commodity as a left-handed reliever, Affeldt likely could have coaxed a more lucrative offer from another team. At age 33 and with a family of three sons, Affeldt wanted financial security, not the uncertainty of a one-year contract or option years. Once the Giants proved willing to give Affeldt a three-year package, as they demonstrated shortly after the World Series ended, the bargaining essentially ended.

"The Giants are aggressive," Affeldt said. "They don't sit there and try to lowball and figure out where to get to, if they have an idea of where [your salary] should be. I don't think Sabean messes around a whole lot."

Affeldt indicated that he could have listened seriously to proposals from other teams. But, as he stated, he didn't have a reason to leave, especially since he and his family like the city, the Bay Area and the ballclub.

"We won a World Series with a bunch of core guys coming back," Affeldt said, citing Buster Posey, Brandon Belt, Brandon Crawford, Pablo Sandoval, Hunter Pence and the pitching staff. "So for me, knowing I can come back to the same team, it's going to be your No. 1 choice. If it were a bunch of free agents and I didn't know what the team was going to look like next year, they might not have been my first choice."

An 11-year Major League veteran who also has performed with Kansas City, Colorado and Cincinnati, Affeldt owns a 10-9 record with a 2.73 ERA and 10 saves in 261 appearances spanning his four seasons with San Francisco.

He finished 1-2 with a 2.70 ERA and three saves in 67 appearances this year. He also allowed just one home run in 63 1/3 innings.

Capable of functioning as a closer, setup man or lefty-on-lefty specialist, Affeldt thrived in the postseason, accumulating 10 1/3 scoreless innings in 10 games.