Carp, 27, mashed to the tune of .296/.362/.523 (140 OPS+) with 18 doubles and nine home runs in 243 plate appearances as a part-time first baseman and part-time corner outfielder for Boston last season. They acquired him from the Mariners in a cash trade last February.
The Pirates have been seeking a left-handed platoon partner for Gaby Sanchez, who managed a .333/.448/.539 batting line against southpaws in 2013. Carp, a lefty hitter, put up a .300/.367/.537 line in 215 plate appearances against righties last season. He and Sanchez would make one productive platoon.
The Brewers are having an open competition at first base in spring training. Juan Francisco, Hunter Morris, Lyle Overbay and Mark Reynolds are among those vying for a roster spot. They've had a revolving door at the position in the two seasons since Prince Fielder left.