Positional series: Can Koji do it again?

This is the fifth in a weekly series evaluating the Red Sox roster by category: infield, outfield, catching, starting pitching, bullpen and DH.

Ah, yes, the genius of the Red Sox, with their formula for building a championship bullpen: Make trades in back-to-back seasons for proven closers, watch them both go down with season-ending injuries within weeks of each other, then place your fate in the hands of a brittle Japanese veteran who was left off the roster the last time he was on a team that went to the World Series.

Works every time. All it takes is for that Japanese veteran, Koji Uehara, to have the type of season that made Mariano Rivera deserve every second of the league-wide sendoff he received in his last year as a Yankee.

What appeared to be a decent but hardly shape-shifting transaction at the time -- the Sox signing Uehara to a one-year, $4.25 million free-agent deal (with a hidden $5 million option for 2014 tucked inside) -- became a franchise saver. Uehara not only filled the void created by the injuries to Joel Hanrahan and Andrew Bailey, he responded with a performance epic in scope.

At 38, Uehara had a record 0.56 WHIP in 73 appearances for the Sox in 2013, nearly double the 37 appearances he made for the Texas Rangers in 2012. Then he came out of the bullpen 13 more times in the postseason, saving seven games in October and winning one while allowing a single earned run (Jose Lobaton’s home run) in 13 2/3 innings. After the All-Star break, he made 29 regular-season appearances, allowed just 9 hits, none of them home runs, and struck out 41 while walking 1. He retired 37 consecutive batters, the equivalent of a perfect game carried into the 13th inning.

Line up any Red Sox closer -- Dick Radatz, Jonathan Papelbon, Flash Gordon, Keith Foulke, anyone else you care to nominate -- and Koji trumped them all. David Ortiz thinks he’s entitled to an extension? Consider what Uehara could have gotten on the open market this winter: Joe Nathan, who at 39 is the same age that Uehara turns on April 3, signed a two-year, $20 million deal with the Tigers.

Keeping Uehara whole, especially after his heaviest workload since 2008, his last season in Japan, will be one of John Farrell’s top priorities this spring. The Red Sox manager already has announced that he will scale back Uehara and left-hander Craig Breslow in camp, looking to keep them fresh as long as possible.

Breslow, like Uehara, stepped up after an injury, becoming the team’s most dependable lefty after Andrew Miller sustained a season-ending foot injury. Breslow posted the best ERA of his career (1.81), his only real hiccup coming at the most inopportune time, the World Series.

With neither Bailey nor Hanrahan returning this season, GM Ben Cherington buttressed the pen with the addition of setup man Edward Mujica, who spent much of last season as the Cardinals’ closer, and Burke Badenhop, a right-handed sinkerballer acquired by trade from the Brewers. Strike-throwing remains a priority: As the 2014 Baseball Prospectus points out, the two newcomers, along with Uehara and Junichi Tazawa, combined for 30 unintentional walks in 269 innings. That computes to a single walk per nine innings.

Miller is fully recovered from his foot injury, according to the club, and is coming back from his best season in the majors, one in which he had fantastic reverse splits, holding right-handed hitters to a .155 average. After walking six batters in his first seven appearances (four innings), Miller showed great progress in harnessing the control issues that have sidetracked him in the past; he walked just two batters in his next 16 appearances and posted a 1.31 ERA in his last 21 appearances, striking out 30 batters in 20 2/3 innings.

Farrell has four legitimate eighth-inning options in Tazawa and Mujica from the right side, Breslow and Miller from the left. Badenhop and whichever starter does not crack the rotation -- Ryan Dempster finished the season in the bullpen -- offer Farrell length, and there are a host of young arms that will be bidding for the kind of opportunity that rookies Brandon Workman and Drake Britton ran with last season.

There is depth here, and quality depth, the same component that made the Sox bullpen so successful last season. Uehara may have had a once-in-a-lifetime season -- what’s the Japanese version of Joe Hardy? -- but whatever might occur, the Sox appear prepared to deal with it.