The Mets agreed yesterday to a minor league contract with Bret Boone, a move that shows how tenuous Kaz Matsui’s hold on second base is. A three time All-Star and four-time Gold Glove winner, Boone’s career has plummeted since the 2003 season. He was cut by the Seattle Mariners on July 3, dealt to Minnesota eight days later, then released by the Twins on August 1. He batted .221 with seven homers and 37 RBI in 326 plate appearances.

“I don’t know if he could rebound, but to bring in a guy with his history on a minor league contract, I figured, what is there to lose?” GM Omar Minaya said. “There’s something about Bret that I’ve always liked. He wants to prove that last year was not his year.”

If added to the 40-man roster, the 36-year-old Boone would get a $1 million salary and the chance to make $500,000 in performance bonuses, a fraction of the $9.25 million he earned last year.

Matsui has had two subpar seasons with the Mets, hitting .255 with three homers and 24 RBI last year. He was on the disabled list from mid-June to August 9 because of a bruised left knee, and there has been repeated speculation that the Mets will trade him. He is owed $8 million this year, complicating any trade talks.

Boone hit 19 or more homers in seven straight seasons through 2003 and topped 100 RBI from 2001-03, driving in a career-high 141 runs in 2001, when he hit 37 homers.

Minaya said manager Willie Randolph will decide on the starter.

“Matsui’s got to go out there and play. It’s not that Matsui has the job won,” Minaya said. “You try to say that Matsui last year had an off year. He was injured part of the year, and I think if you ask Willie today, there’s a competition out there.”

The Mets also bolstered its bullpen yesterday by acquiring right-handed relievers Duaner Sanchez and Steve Schmoll from the Los Angeles Dodgers for right-hander Jae Seo and left-handed reliever Tim Hamulack.

Sanchez joins Aaron Heilman and Chad Bradford as setup men for new closer Billy Wagner. It was unclear whether the Mets were still trying to acquire Danys Baez from Tampa Bay.

“I pursued other things, but this one was in front of me,” Minaya said. “The others that were out there never came to fruition. I had to make a choice: either wait for something else or get something that we’ve liked all along.”

Seo, 28, made 14 starts for the Mets last season, going 8-2 with a 2.59 ERA, 16 walks, and 59 strikeouts in 90 1/3 innings. He also was 7-4 with a 4.29 ERA in 19 starts for Triple-A Norfolk. Seo, who went 5-10 with a 4.90 ERA in 2004, has a 22-24 career record and 3.85 ERA in 66 starts and five relief appearances, all with the Mets.

The 26-year-old Sanchez was 4-7 with a 3.73 ERA and eight saves in 79 games last season, tying him for second in the NL in appearances, and he served as the Dodgers’ closer late in the year. He was a setup man in 2004, going 3-1 with a 3.38 ERA in 67 games.

The 25-year-old Schmoll, signed by Los Angeles in May 2003, was 2-2 with a 5.01 ERA and three saves for the Dodgers and 0-3 with a 4.78 ERA in 22 games for Triple-A Las Vegas last season.