The 32-year-old Barrett hit .202 with two home runs and nine RBIs in 30 games with San Diego. He has played 11 seasons in the majors with Montreal, the Chicago Cubs and the Padres.
The 31-year-old Maroth is 50-67 with a 5.05 ERA in six seasons with Detroit and St. Louis. The left-hander pitched three games this year for Kansas City's Triple-A Omaha team in an injury-shortened season.
Ruiz, 31, made his major league debut with Minnesota this year, hitting .274 with one homer and seven RBIs in 22 games. At Triple-A Rochester, he hit .320 with 17 home runs and 68 RBIs.
Chavez, 35, hit .259 with one homer and 10 RBIs for Pittsburgh and has spent parts of 10 seasons in the majors.