The team was unable to trade the 37-year-old, who hit .254 with four home runs and 31 RBIs in 72 games.
Pierzynski was signed by the Red Sox during the offseason to a one-year, $8.25 million contract.
Frasor, 36, had a 3.34 ERA in 38 games with the Rangers, including 30 strikeouts in 29 1/3 innings.
Fernandez, 24, was 0-1 with a 7.00 ERA, seven saves and 20 strikeouts over 29 relief appearances in 27 innings this season with Class A Modesto in the Rockies organization.
Fernandez, a native of Boca Chica, Dominican Republic, spent the 2008 season as a catcher before being converted to a pitcher full-time in 2009.
(Editing by Gene Cherry)