The acquisition of the switch-hitting Herrera gives the Red Sox some protection in the event free agent Stephen Drew does not return to the team.
Originally a second baseman, Herrera, a 29-year-old native of Venezuela, also has played shortstop and third base. In each of the last two seasons, he played the majority of his games at short, appearing in 42 games in both 2012 and '13, starting 34 at short in 2012 and 28 in '13 behind Troy Tulowitzki.
If the Red Sox opt to start the season with Will Middlebrooks at third base and Xander Bogaerts at short, Herrera would back them up. If Boston re-signs Drew, Herrera also could back up Dustin Pedroia at second base.
Herrera played in 81 games last season in Colorado, hitting .292 with a .700 OPS in 195 at-bats. He never has played in more than 104 games in a season. Herrera has a career .265 average with eight homers, 66 RBIs and a .657 OPS in 375 games.
Morales, who turns 28 on Jan. 24, was plagued by neck, back and shoulder issues in the 2½ seasons since the Red Sox purchased him from the Rockies on May 19, 2011. The injuries prevented him from playing a significant role in the team's bullpen, and with left-hander Andrew Miller expected back from his foot injury next season, Craig Breslow on board for a second year and Drake Britton getting some big-league experience in 2013, Morales was deemed expendable. He is a year away from free agency.
The 27-year-old Martin split time between the Double-A Portland Sea Dogs and Triple-A Pawtucket Red Sox in 2013, pitching a combined 72 relief innings in 42 games. He had a 2.25 ERA with 47 strikeouts and 10 walks. He was great in the Dominican Winter League, earning six saves in eight innings without giving up an earned run. He allowed three hits during that span, striking out eight and walking none.
A 27-year-old former independent league pitcher, Martin went 2-0 with three saves in 21 scoreless innings for Portland before being promoted to the PawSox, with whom he went 3-3 with two saves and a 3.18 ERA, striking out 47 and walking 10 in 51 innings. He also pitched in the Dominican this winter, making eight scoreless appearances for Escogido before shutting it down.