Koji UeharaThe Boston Red Sox’s bullpen — outside of closer Koji Uehara — looked like an area of concern at the end of the 2013 regular season. The unit proved to be an area of strength during the club’s World Series run, though, and the Red Sox added some reinforcements over the offseason.

Burke Badenhop and Edward Mujica are among those joining the Red Sox’s bullpen mix, while Andrew Miller, who missed the tail end of last season with a foot injury, also will re-enter the picture. Pitchers Francisco Cordero, Jose Mijares, Rich Hill and Dalier Hinojosa, among others, are expected to compete for the final one or two spots in the bullpen.

Uehara’s 2013 season was historic, so it’ll be interesting to see what he has in store for an encore, especially given that he’s coming off a career-high workload. Junichi Tazawa and Craig Breslow were used extensively down the stretch and into the postseason, too, so manager John Farrell might be forced to limit their innings at the beginning of spring training.

Bullpens are difficult to gauge on an annual basis, as the most impactful additions often fly under the radar at the time the moves are made. Uehara is a perfect example.

Let’s dive into the Red Sox’s bullpen situation for 2014 and beyond.

Depth chart

Closer: Koji Uehara
Edward Mujica
Junichi Tazawa
Craig Breslow
Brandon Workman
Burke Badenhop
Andrew Miller

On the bubble: Francisco Cordero, Jose Mijares, Rich Hill, Tommy Layne, Brayan Villarreal, Chris Resop, Shunsuke Watanabe, Alex Wilson, Drake Britton, Rubby De La Rosa, Steven Wright

First, the Red Sox must decide how many pitchers they’re going to carry to open the season. If they opt for 12, it’ll mean seven relievers — in addition to the five starters (Jon Lester, Clay Buchholz, John Lackey, Felix Doubront and Jake Peavy) — will make the cut. In that scenario, the Red Sox would be forced to roll with a four-man bench, meaning the loser of the outfield battle between Jackie Bradley Jr. and Grady Sizemore — two left-handed-hitting center fielders — could be on the outside looking in. Mike Carp is another potential roster casualty under those circumstances, although he certainly proved valuable in a bench role last season.

Uehara, Mujica, Tazawa, Breslow and Workman seemingly are locks for bullpen spots. That means everyone else is competing for either one or two spots, depending on how many pitchers the Red Sox decide to carry. Miller, assuming he shows he’s fully healthy during spring training, is the most logical fit for the sixth spot because he was solid before going down last season, and he’d give the Red Sox a second left-hander behind Breslow. Badenhop, who was acquired from the Milwaukee Brewers over the offseason, also is a candidate to lock down one of the final spots.

The pitchers listed as “on the bubble” don’t seem to have inside tracks on roster spots for various reasons, but each could force the Red Sox to reconsider their stance with a good spring. The bullpen tends to be the most fluid aspect of a major league roster, and it’s reasonable to think that several of the “on the bubble” players could find their way onto the major league roster at some point.

Uehara, obviously, will be the Red Sox’s closer. Mujica, who was signed to a two-year, $9.5 million contract over the offseason, has experience closing, though, so he’ll represent a solid late-inning option who could slide into the closer role if something unforeseen happens or if Farrell chooses to limit Uehara’s innings early in the season.

Workman likely will begin the year in the bullpen, but he’s essentially the Red Sox’s sixth starter. If something happens within the starting rotation, Workman likely will be the first guy to fill in.

Points of optimism

-Uehara was absolutely dominant last season.

One could point to any number of statistics to show how lights-out Uehara was both during the regular season and in the playoffs. He led all major league relievers in ERA (1.09), WHIP (0.57) and strikeout-to-walk ratio (11.2), and his 44 perfect outings set an American League record. Uehara also tossed 30 1/3 consecutive scoreless innings at one point, holding opponents to a .063 (6-for-95) average in the process.

We’ll stop there for the sake of space.

-Tazawa led all Red Sox relievers and ranked seventh in the American League with 25 holds. He hit a rough patch later in the year, particularly when he was asked to pitch on back-to-back days, but Taz was solid for the most part.

-Breslow was one of the most underrated players on the Red Sox for much of 2013. His 1.81 ERA was a personal best, and the southpaw came up big against the Tampa Bay Rays in the ALDS.

-Workman shined both as a starter and as a reliever in his first major league season. The 24-year-old’s poise was particularly impressive, as he didn’t allow an earned run in 8 2/3 innings in the playoffs.

-Mujica, who was fantastic at the beginning of last season (1.73 ERA going into September), is similar to Uehara in that he pounds the strike zone. The 29-year-old issued just five walks in 64 2/3 innings — equating to a 0.70 walk rate — in 2013, which was far and away the best mark in baseball.

-Badenhop, who posted a 2.05 ERA over his final 21 appearances last season, also brings control to the Red Sox’s bullpen. His 1.7 walks per nine innings since the start of 2012 are good for fifth among major league relievers with at least 115 innings in that span.

Badenhop and San Francisco Giants closer Sergio Romo are the only two pitchers to appear in at least 60 games while allowing less than one home run per nine innings and two walks per nine innings in both 2012 and 2013.

-Miller was limited to 37 appearances last season because of a foot injury he suffered in July, but he enjoyed a career renaissance before that point. The tall lefty averaged a career-high 14.1 strikeouts per nine innings, the second-highest mark among all major league relievers with at least 30 innings pitched — trailing only Aroldis Chapman (15.83)

-Britton, De La Rosa and Allen Webster all are young with high ceilings as starters. But all also gained experience in the bullpen last season. Britton led the trio with 18 major league appearances in 2013.

Points of skepticism

-Uehara was incredible last season. But he’s also turning 39 in April and coming off a season in which he worked his fingers to the bone.

Uehara set regular-season career-highs in appearances (73) and innings pitched (74.1) before then tossing 13 2/3 innings over 13 pressure-packed playoff appearances.

-Tazawa elevated his game in the postseason, but it wasn’t before he struggled in September. Tazawa posted a 6.75 ERA (eight earned runs in 10 2/3 innings) over his final 14 regular-season appearances, showing both diminished velocity and a less effective splitter than usual during that stretch.

-Tazawa was 1-3 with a 10.13 ERA and six home runs allowed in nine appearances against the Toronto Blue Jays last season. Those Jays once again are on the schedule 19 times.

-Tazawa and Breslow, like Uehara, were used extensively at the end of last season. Fatigue isn’t out of the question given the short offseason.

-Workman said in Fort Myers that he’s prepared to pitch in relief or as a starter. He probably isn’t lying, but one has to wonder if him bouncing back and forth too much could stunt his overall development.

(Ditto for other young pitchers, like Britton, De La Rosa and Webster.)

-There’s a reason Mujica lost the closer job with the Cardinals toward the end of last season. While the 29-year-old was terrific at the beginning of the year, he struggled mightily down the stretch.

Mujica’s ERA ballooned from 1.73 on Aug. 26 to 2.78 on Sept. 28. It’s part of a somewhat concerning trend, as Mujica has a 5.14 ERA (43 earned runs in 75 1/3 innings) in 62 career regular-season appearances in September/October — much higher than his overall career ERA of 3.75.

-Miller said earlier in the offseason that he’s 100 percent. However, there’s always a chance his foot injury could linger or he could revert back to being the pitcher who was vehemently labeled a first-round bust before arriving in Boston in 2012.

-Wright already is dealing with an injury, as the knuckleballer underwent a procedure for a sports hernia. He might not be ready to pitch until May.

Reasonable expectations for 2014

First off, don’t expect Uehara to be as good in 2014 as he was in 2013. This isn’t to say Uehara won’t again be masterful as the Red Sox’s closer. It’s just unreasonable to anticipate another historic season.

That being said, the Red Sox’s bullpen has the potential to be one of the American League’s steadiest relief corps if Breslow and Tazawa near their 2013 production, Miller goes back to being a strikeout machine and Workman shows the same poise he demonstrated in Year 1.

The newcomers — as is typically the case with relievers arriving in Boston — are wild cards, especially Mujica, whose 2013 season ended on a sour note. They should only enhance the unit’s overall depth, though.

Position beyond 2014

There are a lot of moving parts when it comes to major league bullpens. Only elite relievers receive lucrative, long-term contracts, and teams typically view the bullpen as an area in which they can be cost-effective by using minor leaguers or low-risk, high-reward veterans.

Uehara, Breslow, Badenhop and Miller are free agents after this season. Mujica is under contract through 2015, Tazawa is under team control through 2016, and Workman likely will be arbitration-eligible for the first time following the 2015 season.

It’s possible Uehara’s second season in Boston could be his last, especially if he has a significant drop-off in production. Uehara’s stuff — which is based more on deception than overpowering hitters — should allow the right-hander to pitch into his 40s, but Father Time could creep into the equation at some point, particularly if the Red Sox continue to rely so heavily on him.

Uehara fell into the closer role in 2013 after Joel Hanrahan and Andrew Bailey — both of whom were ineffective — went down with injuries and Tazawa’s crack at the job proved underwhelming. Uehara’s departure would leave the Red Sox with a major hole to fill, and it’s likely the club would look internally to fill the void.

Workman certainly has the poise to be a closer, and perhaps the Red Sox will consider him as an option given their surplus of other younger starting pitchers. Workman still projects as a future starter, though, so the more likely scenario would be someone like De La Rosa grabbing the ninth-inning reins. De La Rosa has overpowering stuff, and the Red Sox ultimately might decide this season that his future is in the bullpen rather than the rotation.

Down on the farm

Notables: Hill, Layne, Villarreal, Resop, Watanabe, Wilson, Britton, De La Rosa, Webster, Wright, Hinojosa, Noe Ramirez

Webster got a feel for the bullpen last season, but he’ll be a starter to begin this season and will remain a starter unless he suddenly goes off the tracks. De La Rosa and Britton, however, are candidates to join the Red Sox’s bullpen if something happens to one of the club’s major league relievers.

Watanabe, a 37-year-old submarine-style pitcher, is an intriguing player to watch, if for no other reason than he has perhaps the lowest arm slot on the planet.

Hinojosa, a Cuban defector who signed with the Red Sox last October, could factor into the club’s late-season bullpen plans, although it’s unclear at this point whether the 27-year-old will mostly be a reliever or starter in the States.

Ramirez, who figures to start the season at Double-A Portland, is worth keeping an eye on after an impressive Rookie Camp. The 24-year-old struck out 157 batters in 160 1/3 innings in his first two seasons in the Red Sox system. That includes 75 strikeouts in 75 2/3 innings between High-A Salem (21 games) and Double-A Portland (15 games) in 2013 — his first action out of the bullpen.

Editor’s note: NESN.com will provide an organizational outlook for each position in the days leading up to the Red Sox’ first full-squad spring training workout. The schedule for the outlooks is below. Click the links to view each outlook.

Monday, Feb. 10: first base
Tuesday, Feb. 11: second base
Wednesday, Feb. 12: third base
Thursday, Feb. 13: shortstop
Friday, Feb. 14: outfield
Monday, Feb. 17: catcher
Tuesday, Feb. 18: starting rotation
Wednesday, Feb. 19: bullpen

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