Astacio, 36, is 124-119 with a 4.61 career ERA. He was 4-2 with a 3.17 ERA in 12 games, starting 10 times and pitched Game 2 of the National League Division Series in St. Louis, losing to the Cardinals.
The Padres, who reportedly have offered him a $1.5 million deal, have negotiating rights to Astacio through Jan. 8. He was 2-8 with a 6.04 ERA with the Rangers when he was released on June 21 and signed nine days later by San Diego.
An offer was estended, as expected, to catcher Miguel Olivo. Breslow, Brazelton, Ross and Laforest become free agents.
Olivo figures to share catching duties with newly acquired Doug Mirabelli. Acquired from Seattle at the trade deadline last July to fill in for injured Ramon Hernandez, Olivo exceeded expectations. The 27-year-old batted .304 with four homers and 16 RBIs in 115 at-bats, impressing manager Bruce Bochy with his work ethic and desire to excel.
Breslow, signed for $1 out of a tryout camp after getting released by the Brewers, is a 25-year-old southpaw who pitched capably for the Padres in a brief stint in 2005. He had a 2.20 ERA in 16 1/3 innings, striking out 14. With Chris Hammond having left via free agency, the Padres have no returning lefties in the bullpen.
Ross appeared in 11 games after coming from the Pirates in another acquisition designed to ease the loss of Hernandez. Ross batted .241 in 51 games with the Pirates and Padres.
Another veteran receiver, Laforest was recently acquired from the Devil Rays. A left-handed hitter, he batted .172 in 25 games at Tampa Bay.
Brazelton, a former first-round pick in the First-Year Player Draft, was acquired from Tampa Bay at the Winter Meetings for third baseman Sean Burroughs.
The Devil Rays' Opening Day starter last season, Brazelton finished the season with a 1-8 record and 7.61 ERA.