Napoli, 31, brings a powerful bat to the Boston lineup, along with the flexibility to catch or play first base. He also could serve as the designated hitter on days when David Ortiz does not play.
Napoli was an All-Star and had an .812 OPS and 24 home runs with the Texas Rangers this past year — his fifth straight season with 20 or more homers. His arrival in Boston increases the chances that Red Sox catcher/first baseman Jarrod Saltalamacchia will be dealt this offseason.
Napoli spent the past two seasons with the Rangers, who now face an intriguing decision on free agent Josh Hamilton as they try to maintain a formidable lineup. If Hamilton also signs elsewhere, then the Rangers could intensify their efforts to acquire Justin Upton from the Arizona Diamondbacks.