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10/30/10 11:06 PM ET

Bumgarner's success belies his age

ARLINGTON -- He's the reason why a $126 million pitcher is nowhere to be found on the Giants' postseason roster, the reason why arguably the best pitcher in baseball isn't needed on short rest on baseball's grandest stage, and he could help put the Giants one win away from their first championship since they moved West more than five decades ago.

Oh, and he's only 21 years old.

His name is Madison Bumgarner. He's the Giants' fourth starter in these playoffs, and he's been pitching completely out of his mind since rejoining a Major League roster, especially since the stretch run of the regular season.

On Sunday, he'll get the ball here for Game 4 of the World Series (5 p.m. PT on FOX) and oppose Texas' Tommy Hunter in a crucial swing game. Win, and the Giants are up 3-1 with two home games to play. Lose, and we basically start all over again in best-of-three fashion.

Calling the signals for Bumgarner will be his 23-year-old fellow-rookie backstop Buster Posey. At a combined 44 years, the Giants' Game 4 battery will become the second youngest pitcher-catcher combination in World Series history, behind Jim Palmer and Andy Etchebarren, who were a combined 43 years old when they teamed up in Game 2 of the 1966 World Series for the Baltimore Orioles.

"We'll see what happens," Giants manager Bruce Bochy said after losing, 4-2, on Saturday night to move the Series to 2-1. "You know, it's nice to be in our position right now, but we said we have a lot of work ahead of us."

Tale of the Tape: World Series Game 4
2010 Regular Season
Overall: 23 G, 22 GS, 13-4, 3.73 ERA, 33 BB, 68 K
Overall: 18 GS, 7-6, 3.00 ERA, 26 BB, 86 K
Key stat: Was perfect (7-0) at home this season until ALDS loss
Key stat: Held lefty batters to .243 batting average in regular season
2010: 2 GS, 0-1, 6.14 ERA
Career: 2 GS, 0-1, 6.14 ERA
2010: 3 G, 2 GS, 1-0, 3.55 ERA
Career: 3 G, 2 GS, 1-0, 3.55 ERA
2010: 13 G, 12 GS, 7-1, 3.14 ERA Career: 25 G, 24 GS, 13-5, 3.72 ERA
2010: N/A Career: N/A
Against this opponent
2010: N/A Career: N/A
2010: N/A Career: N/A
Loves to face: Cody Ross (0-for-1)
Hates to face: Pat Burrell (1-for-3)
Loves to face: N/A
Hates to face: Jorge Cantu (1-for-3)
Game breakdown
Why he'll win: Comfortable at home ballpark
Why he'll win: Young lefty has shown no fear
Pitcher beware: Has pitched poorly in postseason thus far
Pitcher beware: Has struggled (.322 BA, .355 OBP) to put leadoff hitters away
Bottom line: Home sweet home
Bottom line: Confident rookie

That work will continue with Bumgarner, as unlikely as that may have seemed in late March. At that point, Bumgarner was optioned to the Minor Leagues after an unimpressive Spring Training. Now, he's starting in the World Series.

"It's been amazing," Bumgarner said in his press conference prior to Game 4. "But right now, I'm just going to try to treat it like any other game, and then after it's over with, look back and be like, 'Wow, you just pitched in the World Series.'"

Sunday's matchup will actually feature two starters who began this season pitching in the Minors.

Bumgarner, who dazzled in his short, late-season sample size in 2009, went into Spring Training competing for the fifth starter's spot but came up short. Then, after going 7-1 with a 3.16 ERA in 14 starts for Triple-A Fresno, he game back up in June and proved he should stay.

Bochy feels the biggest reason was that the young left-hander got in better shape.

"He came into the spring, I think, with the idea he'll get in shape there," the Giants' skipper said. "He was a guy that we were strongly considering being our fifth pitcher in the rotation. We didn't think he was quite ready. And so to his credit, he went down, worked hard in Fresno, and he got in better pitching shape, and I think that's the biggest difference."

Bumgarner went on to finish the season 7-6 with a 3.00 ERA in 18 starts, including a 1.18 ERA in his final six outings. That was all Bochy needed to see to take the high-priced, struggling Barry Zito off his postseason roster and decide he didn't really have to go with Tim Lincecum on short rest to win these playoff series.

Bumgarner has rewarded his manager's confidence.

He gave up two runs in six innings during the Game 4 National League Division Series clincher against the Braves, left the fifth inning with a 2-1 lead in an eventual win over the Phillies during Game 4 of the NL Championship Series, then hurled two shutout innings of relief in Game 6 -- preserving a 2-2 tie in the fifth and sixth -- to help send the Giants to their fourth World Series since moving West in 1958.

Now here he is.

"It's been a fun ride," said Bumgarner, who grew up a Braves fan but said he eventually just "liked to watch good players, good pitchers mostly," including Cliff Lee.

"This is where you want to be, but it definitely has exceeded my expectations."

Bumgarner, a highly touted prospect all throughout his pro career, will take the mound Sunday in front of a hostile road crowd desperate for their team to even up this best-of-seven series.

But it seems he prefers it that way.

During the regular season, his ERA was 4.60 at home and 1.91 on the road. And in the playoffs, the only time he had any struggles -- when he gave up three runs in 4 2/3 innings in Game 4 of the NLCS -- came while pitching at AT&T Park.

But he's never pitched in this ballpark, he's never faced the Rangers, he's never gone up against anybody who was in their starting lineup Saturday, and he's of course never pitched in the World Series.

Will that seep into his mind at all Sunday?

"The only time I've really thought about it is when I've been asked about it," Bumgarner said. "Any other time, I try to just forget about it because we've got to take it one game at a time. I know it's kind of cliche, but you've got to do it."

Alden Gonzalez is a reporter for MLB.com and writes an MLBlog, Gonzo and 'The Show'. Follow him on Twitter @Alden_Gonzalez. This story was not subject to the approval of Major League Baseball or its clubs. This story was not subject to the approval of Major League Baseball or its clubs.