SEATTLE -- Mariners general manager Jerry Dipoto on Monday made his first moves to open space on the 40-man roster for offseason maneuvering. Four players were assigned outright to the Minor Leagues to reduce the roster to 34.

Catchers Joe Hudson and Joseph Odom and right-handed pitchers Seth Frankoff and Brady Lail were assigned to Triple-A Tacoma. Hudson and Lail, however, elected to become free agents. Odom and Frankoff also will have the opportunity to become free agents but can’t do so until after the World Series. Hudson and Lail were able to file for free agency immediately because they previously had been outrighted by other clubs.

Dipoto needs to open spots on the 40-man roster in order to sign free agents or make trades this winter, as well as to create space for the return of eight players on the 60-day injured list. Those eight -- catcher Tom Murphy; outfielder Mitch Haniger; and pitchers Gerson Bautista, Nestor Cortes, Taylor Guilbeau, Andres Muñoz, Matt Magill and Carl Edwards Jr. -- must be reinstated to the 40-man roster five days after the end of the World Series or must be designated for assignment at that time.

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The Mariners will gain another opening on the 40-man roster when reliever Yoshihisa Hirano becomes a free agent after the World Series. Further openings are possible if the club doesn’t pick up option years on the contracts of second baseman Dee Strange-Gordon and right-hander Kendall Graveman.

The four players outrighted on Monday all played limited roles for the Mariners during the 60-game season. Odom and Hudson were added to the Major League roster several times to fill the backup role at catcher. Odom played in 18 games in his first season in the Majors at age 28, hitting .128 with two RBIs in 39 at-bats. Hudson, 29, appeared in nine games and hit .176 in 17 at-bats.

Lail and Frankoff were midseason additions. Lail, 27, posted a 4.80 ERA over 15 innings in seven appearances after being claimed off waivers from the White Sox on Aug. 10. Frankoff, 32, pitched twice in relief, allowing five earned runs in 2 2/3 innings. He spent the previous two seasons in Korea and signed a Minor League deal with Seattle on Aug. 11.