Napoli, 32, has helped his teams reach postseason play in six of the last seven years. He homered twice this past October, including a solo shot off Justin Verlander to provide the Sox with a 1-0 win in Game 3 of the ALCS in Detroit. In 47 career postseason games, he has hit .254 (35-for-138) with six doubles, seven homers, and 26 RBI.
During the regular season, Napoli finished second on the club to David Ortiz in home runs, RBI, slugging percentage (.482), and OPS (.842).
Napoli led the majors last season with a career-high 4.59 pitches seen per plate appearance, the highest average by a Red Sox and the third-highest by a major league qualifier since the stat began being tracked in 1988 (Brett Gardner, 4.61 in 2010; Rickey Henderson, 4.60 in 1994). Among active major leaguers with at least 1,500 plate appearances, Napoli's average of 4.32 pitches per plate appearance trails only Jayson Werth (4.42).
A two time American League Co-Player of the Week in 2013, Napoli led the AL and tied for the major league lead with three grand slams. His six games with at least four RBI last season tied for the most in MLB, and he averaged the sixth-fewest at-bats per RBI in the AL (5.4).
The native of Hollywood, FL has the eighth-best OPS in the AL over the last three seasons at .895, and he is one of only four AL qualifiers to average fewer than eight at-bats per extra-base hit in that span (7.97 AB/XBH), along with Ortiz (7.23), Miguel Cabrera (7.51), and Chris Davis (7.82).
Last season, as a full-time first baseman for the first time in his career, he led the majors in ultimate zone rating at the position (9.7). He had caught at least 60 games in each of his previous seven seasons in the majors.
An eight-year major league veteran, Napoli has hit .259 with 151 doubles, eight triples, 169 home runs, and 472 RBI in 866 career big league games. Before joining the Red Sox, Napoli spent two seasons with Texas from 2011-12, where he was an All-Star in 2012. He began his big league career with a five-year stint with the Angels from 2006-10.
Napoli is one of 11 major leaguers with at least 20 home runs in each of the past six seasons. In the AL, only Jose Bautista (13.4) and Miguel Cabrera (15.5) have averaged fewer at-bats per home run than Napoli (16.0) during that span (min. 2,000 PA). Since 2008, Napoli ranks sixth among AL leaders with a .513 slugging percentage.
Castellanos, 27, was acquired from the Dodgers on October 23 in exchange for minor league outfielder Jeremy Hazelbaker and cash considerations. The right-handed batter has hit .171 (7-for-41) with one double, one triple, two home runs, and four RBI in 24 career major league games, all with Los Angeles over the past two seasons.