FORT MYERS, Fla. -- The Boston Red Sox added another left-handed-hitting first baseman/outfielder to the mix of players already auditioning for backup roles, acquiring Mike Carp from the Seattle Mariners on Wednesday for a player to be named later or cash considerations.

The Red Sox moved outfielder Ryan Kalish to the 60-day disabled list to make room for Carp on the 40-man roster.

At first blush, Carp doesn't appear to be an upgrade over the players already competing for the spot -- Daniel Nava, Mitch Maier, Mark Hamilton and Lyle Overbay (the latter three are non-roster players with an invitation to Boston's big league camp).

Red Sox manager John Farrell said that although the team is looking primarily for a left-handed hitter to face right-handers, and Carp actually has a better career average against lefties, he was acquired because defensive versatility is as important as offensive production.

"It increases the competition, particularly at first base and left field," manager John Farrell said. "We've had a chance to talk to some other guys that might be directly impacted by that, but we've been able to add a talented player to camp here -- someone we've had conversations about throughout the course of the offseason, and finally he became available. So another left-handed hitter who has that versatility on the defensive side.

"Personally, I have seen a very good approach at the plate -- a guy that doesn't seem to be overexposed with one certain type of pitch thrown."

When Carp makes contact, the ball tends to travel long distances. Of the 12 home runs he hit for the Mariners in 2011, all went at least 385 feet, and nine cleared 400 feet, according to Baseball Prospectus.

But Carp missed 79 games last season because of shoulder and groin injuries -- he hurt his throwing shoulder diving for a ball in spring training -- and was designated for assignment by the Mariners, a team starved for offense. The injuries limited Carp to just 59 games for Seattle; he batted .213 with five home runs in 189 plate appearances. In 35 games at Triple-A Tacoma, he batted .223 with two homers in 139 plate appearances.

Carp is not regarded as a solid defender at first, which may be problematic for a team that is already relying on Mike Napoli, who has very limited experience at first. Carp, however, is regarded as an adequate outfielder.

Carp is only 26, and in 2011 the Mariners used him for a time as their cleanup hitter.

The Mariners were so convinced that Carp was not the answer that they added three players this winter -- Michael Morse, Kendrys Morales and Raul Ibanez -- who play the same position.

Overbay, who signed a minor league contract earlier this winter, said Wednesday he doesn't feel threatened by the signing of Carp.

"I haven't even thought of it," Overbay said. "It just depends. I don't want to sit here and say that yeah, that works for him. He has to come in and prove it, too."

Carp's agent, Tom O'Connell, who also represents Red Sox right-hander Alfredo Aceves, was in camp Monday pitching Carp to Red Sox general manager Ben Cherington.

Carp is expected to arrive in time for Thursday's exhibition doubleheader against Northeastern and Boston College. He is out of minor league options, as is Nava.

Information from ESPNBoston.com spring training contributor Rick Weber was used in this report.