By Wendy Thurm

The Red Sox beat the Tigers on Tuesday on the strength of a solo home run by Mike Napoli off Justin Verlander in the seventh inning. Boston took a 2-1 lead in the ALCS heading into Wednesday's Game 4 in Detroit. Red Sox starter John Lackey pitched the game of his life, outdueling Verlander, who hadn't given up a run in his prior 33 1/3 innings. But Boston manager John Farrell lifted Lackey after 6 2/3 innings and handed the ball to three relievers: Craig Breslow, Junichi Tazawa and Koji Uehara. They blanked the Tigers and finished the job.

Uehara was also key to the Red Sox's come-from-behind victory Sunday in Game 2. With Fenway Park still shaking from David Ortiz's game-tying grand slam, Uehara needed just nine pitches to retire Don Kelley, Austin Jackson and Torii Hunter in the top of the ninth and was the winning pitcher when the Sox scratched a run across in the bottom of the inning. Brandon Workman and Felix Doubront kept the game close and gave the Red Sox a chance, after starter Clay Buchholz coughed up five runs in 5 2/3. Neither Workman nor Doubront allowed a hit or a run.

Breslow, Tazawa, Workman, Doubront and Uehara. Not household names outside Boston. Perhaps not within the Hub either. But they will play as big a role in the outcome of the ALCS as the Red Sox's league-leading offense, the starting pitching, and the beard tugs. Yes, even the beard tugs.

Who is Koji Uehara? Just the most effective relief pitcher in the majors this season. Batters hit only .129 against Uehara and he yielded just more than one run per nine innings. He struck out 38.1 percent of the batters he faced, second only to the Royals' Greg Holland. That's why my "out of left field" prediction for the postseason was that Uehara would win both the ALCS and World Series MVP.

Uehara's secret is a devastating splitter that starts in the zone and then falls as quickly as an amusement park drop zone. Uehara used the splitter to strike out Prince Fielder with runners on first and third, and two outs, in the eighth inning of Game 3, with the Red Sox clinging to a 1-0 lead.

The 38-year-old Osaka, Japan-native is in his first season with the Red Sox, after four years split between the Orioles and the Rangers. He began his professional career in Japan, and pitched for the Yomimuri Giants for 10 seasons before coming to the U.S. in 2009.

Since late June, Uehara's worked his pitching magic in the ninth inning or later, as the Red Sox' closer. But that wasn't the plan drawn up in spring training by GM Ben Cherington and Farrell. Boston traded for Joel Hanrahan over the winter and expected he would carry the laboring oar at the back end of the bullpen. The winter prior, the Red Sox obtained Andrew Bailey from the Athletics with the same expectation. Bailey's 2012 was marred by a shoulder injury, thumb surgery and a strained biceps. He pitched just 15 innings. Hanrahan saw even less action in 2013. He threw only seven innings before having season-ending Tommy John surgery in May. Bailey then came back from the biceps soreness and suffered another season-ending injury, this time to his shoulder capsule. In stepped Uehara. Out went the Red Sox' opponents.

Uehara wasn't the only reliever asked to step up after the season-ending injuries to Hanrahan, Bailey and Andrew Miller, another bullpen regular. Workman made his big-league debut in July, made a few spot starts while Buchholtz was injured and then quickly moved into a late-inning role. Tazawa threw more than 68 innings, almost all in the seventh inning or later -- a 50 percent increase over his innings pitched in 2012. And Breslow did whatever Farrell needed him to do.

For all the changes, all the mixing and matching, all the high-leverage situations, it worked. In the second-half, the Red Sox bullpen accumulated 3.4 Wins Above Replacement (as calculated by FanGraphs), third in the majors behind the Royals and the Rangers.

They've been better in the postseason. Through four ALDS and three ALCS games, Red Sox relievers have thrown 19 1/3 innings and allowed just two runs. And those two runs were scored in the same game -- Game 3 of the ALDS against the Rays. In the remaining 18 1/3 innings, they've been nearly perfect.

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Wendy Thurm is a contributing writer at FanGraphs and Bay Area Sports Guy. She has also written for ESPN.com, SBNation, The Score, and the Wall Street Journal. You can follow her on Twitter @hangingsliders.