At second base, the plan is to preserve Dustin Pedroia

Dustin Pedroia is under contract for six more years at $84 million, so the Red Sox must think long-term with him. Aram Boghosian for the Boston Globe/Globe Freelance

Third in a series examining the Red Sox roster

That Dustin Pedroia will be their second baseman is something the Red Sox have counted on for nearly a decade now. He has been their Opening Day starter nine years in a row.

Only a handful of Sox infielders have exhibited that level of reliability, and some who have — such as Bobby Doerr and Wade Boggs — are in the Hall of Fame. Only 13 players have played more games for the Red Sox than Pedroia.

At 32, Pedroia is in the later stages of his prime years and still very much an effective player. Among players at his position with at least 425 plate appearances last season, Pedroia ranked sixth with a .797 OPS.

The concern is that Pedroia has missed 119 games over the last four years because of a variety of injuries.

He was on the disabled list with a right thumb sprain in 2012 and played the entire 2013 season with a ligament strain in the same area, getting surgery after the season.

He then missed the final 18 games of the 2014 season after having a second surgery on the same hand.

Pedroia strained his right hamstring last June 24 when he stumbled rounding first base. He was out until July 16 but played only six games before going back on the DL.

That time, Pedroia did not come back until Sept. 7. The Sox were careful with Pedroia, who sat out seven of the remaining 25 games. He hit .308 with an .888 OPS after returning, a good way to go into the offseason and ease any fears about his health.

During the final week of the season, bench coach Torey Lovullo said team officials had already discussed a plan to give Pedroia more days off in 2016 in an effort to keep him healthy and productive.

Controlling his playing time could help slow what has been a slight decline for Pedroia in recent years, one that is clearly related to the injuries.

Pedroia hit .309 with an .846 OPS in the first five full seasons of his career. He made the All-Star team three times, and he and Robinson Cano were the best second basemen in the American League.

In the last four seasons, Pedroia has hit .290 with a .772 OPS and made the All-Star team once. The hand injuries sapped Pedroia of his power during the 2013 and ’14 seasons. He improved last season with a .441 slugging percentage.

The Red Sox have little choice but to think long-term with Pedroia. He is signed through 2021, longer than any other player on the roster. The Sox owe him $84 million over the next six seasons.

That contract appeared to be a bargain when it was agreed to in 2013. How gracefully Pedroia ages will determine whether that is the case.

Do-it-all Brock Holt is the primary backup at second base, and it’s a position he handles well. The Red Sox would be comfortable with Holt playing second base when Pedroia needs a day off.

Deven Marrero, drafted and developed as a shortstop, played 20 innings at second base last season. Marrero has been an outstanding defensive shortstop in the minor leagues and has trade value. If the Sox retain him, the former first-round pick provides depth at the infield positions.

Second base is a fairly deep position in the minor leagues.

Sean Coyle, a third-round pick in 2010, is on the 40-man roster but is in fading from prospect status. Coyle, who turns 24 in January, was limited to 52 games by injuries last season and hit .193.

Marco Hernandez, who was added to the 40-man roster last week, has been primarily a shortstop in the minor leagues. He profiles as a utility player and has 42 games of experience at second base.

Wendell Rijo spent last season with High Single A Salem, hitting .260 with a modest .705 OPS. It was his least productive season since being signed in 2012. Rijo’s best quality has been his offense, so the coming season will be telling for him.

The other second baseman of note is Yoan Moncada. The Sox spent a stunning $63 million to sign Moncada last March. The Cuban hit .278 with 8 home runs and 38 RBIs in 81 games for Single A Greenville.

Moncada stole 49 bases in 52 attempts, which seems astonishing at first glance. But stealing bases against the inexperienced pitchers and catchers of the South Atlantic League is not necessarily a sign of much. Borderline Red Sox prospect Garin Cecchini was 51 of 57 for Greenville in 2012 and has stolen 43 bases in 373 games since.

Moncada played only second base, and that was his primary position in Cuba. With Pedroia seemingly locked in place, Moncada could wind up in the outfield or perhaps at third base when he is deemed ready for the majors.

SECOND BASE

Primary 2015 starter: Dustin Pedroia.

Expected 2016 starter: Pedroia.

Major league depth: Brock Holt, Deven Marrero.

Prospects to watch: Sean Coyle, Marco Hernandez, Wendell Rijo.