"It's definitely not up to me, but any bullpen guy will tell you it's the ideal spot to be," Walker said Tuesday. "It's up to the manager, and we'll see how it plays out in spring training. I'll do it [close] if they want me to. I have no problem with that."

The 6-foot-3, 262-pound Walker, who became a free agent when the Giants removed him from their 40-man roster after the season, joins a late-inning bullpen mix that could include Batista, newly acquired Aaron Heilman, Mark Lowe, Ryan Rowland-Smith and Brandon Morrow. The latter two ended the season in the Seattle rotation and have indicated a preference to start, as has Heilman.

Walker became the Giants' closer in 2005 when Armando Benitez was injured, and he saved 23 games in 28 opportunities. He was traded to Tampa Bay in 2006 and became the Rays' closer, saving 10 games (in 14 chances) before succumbing to elbow problems that resulted in Tommy John surgery.

The Giants re-signed him, and he began last season as their primary setup man. But Walker struggled early and wound up being booed by San Francisco fans. He finished 5-8 with a 4.56 earned-run average in 65 games, striking out 49 in 53-1/3 innings. Walker's nemesis was left-handed hitters, who batted .319 off him.

"When I was released in October, I sat down that day with my agent and gave him a list of teams," he said. "Seattle was right at the top of that list. I'm thankful and happy to be here."

Just before Christmas, Walker held a workout at the University of California, his alma mater, throwing about 30 pitches for Tom Davis, a Mariners area scout. The Mariners liked what they saw and offered him a major-league contract.

"Tyler is a pitcher we had identified early on as a guy who could help us in the bullpen," Mariners general manager Jack Zduriencik said. "He has the ability to pitch in any role middle relief, setup, and he has experience as a closer."

Larry Stone: 206-464-3146 or lstone@seattletimes.com