Beltran, 36, is coming off a 2013 season in which he batted .296/.339/.491 (128 OPS+) with 24 homers and 30 doubles for the Cardinals, whom the Red Sox of course defeated in the World Series. Beltran is also a legendary hitter in the postseason and has cobbled together what should be a Hall of Fame career. With that said, our own Mike Axisa raised some doubts about Beltran's performance outlook moving forward.
From Boston's standpoint, they would get some certainty in an outfield that depended rather heavily upon role players in 2013 and may face the loss of Jacoby Ellsbury via free agency. It's also conceivable that Beltan may be open to playing some first base at this late stage of his career. Some added motivation might also be raising Beltran's price for, say, the rival Yankees or Orioles.
Worth remembering is that the Cardinals made a qualifying offer to Beltran, so if a team other than the Cardinals signs him, then that team will be sacrificing a high draft pick in order to do so.