The two moves are among the first of the offseason housecleaning, as the organization puts in place its plan to shape up the roster.
Lucas and Valdespin became expendable with the addition of Enrique Hernandez to the roster. Donovan Solano could take on a utility role if the Marlins bring in a regular second baseman this offseason.
In the second half, Solano saw a bulk of the action at second base.
Lucas, 32, appeared in 69 games and batted .251 with one home run and nine RBIs. In two seasons with Miami, he hit .255.
A Dartmouth graduate, Lucas was an eighth-round pick of the Royals in 2004. He was set to make Miami's Opening Day roster, but a few days before the season opened, he broke a bone in his left hand after being hit by a pitch.
Lucas plays all four infield spots, as well as the outfield corners. He also was an emergency catcher but never was needed in that role.
Valdespin, who turns 27 in December, saw action at second base with Miami, and he played some outfield down the stretch. A left-handed hitter, he batted .214 with three homers and 10 RBIs in 52 games.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter @JoeFrisaro. This story was not subject to the approval of Major League Baseball or its clubs.