SAN FRANCISCO - Yusmeiro Petit fills what might be the least glamorous role on the Giants' pitching staff.
During the regular season, the 29-year-old righthander worked as the team's primary long reliever and occasional spot starter, a job that often is marginalized during a typical postseason.
Of course, nothing about the Giants' latest playoff run has been typical, which is why Petit has emerged as a savior.
"No doubt he's been our secret weapon,'' reliever Jeremy Affeldt said.
The Giants entered Thursday night's Game 5 of the National League Championship Series needing one more win against the Cardinals to reach the World Series for the third time in the past five seasons. They reached that point thanks to Petit, who has logged a pair of multiple-inning relief stints that spared the Giants from burning through their bullpen.
"He's been a difference- maker,'' Giants catcher Buster Posey said.
Petit first put his stamp on this postseason through his starring role in the Giants' 18-inning classic against the Nationals in Game 2 of the NLDS. Although Brandon Belt bashed a solo shot in the 18th that made it 2-1, it was Petit who put him in position to win it.
Petit entered in the 12th with the score tied at 1, the sixth Giants pitcher. He had no margin for error. He departed after the 17th after striking out seven in six shutout innings.
"You have to be mentally strong to know that one pitch can mean win or loss,'' Petit said earlier this postseason. "That's what you have to do, just sit there and just make sure that you execute and that you make your pitch.''
Petit's mental toughness came into play again Wednesday night in Game 4 of the NLCS. When Ryan Vogelsong was knocked out after three innings, Petit tossed three shutout innings, giving Bruce Bochy a steady bridge to the arms in the back of his bullpen.
For the second time in the playoffs, Petit emerged with a victory.
Said Bochy: "Petit saved us.''
Petit's baseball journey began as a farmhand with the Mets, who signed him out of Venezuela in 2001. Before the 2006 season, the 6-1, 250-pounder was traded to the Marlins along with Mike Jacobs and Grant Psomas for Carlos Delgado. Petit was traded to the Diamondbacks in 2007, claimed off waivers by the Mariners in 2009 and banished to the Mexican League in 2011.
When the Giants signed him to a minor-league deal in 2012, it had been two years since he'd appeared in a big-league game. In seven seasons, he's 19-26 with a 4.76 ERA. He has never been a particularly hard thrower; his fastball tops 90 mph on a good day. He relies primarily on steady command.
Nevertheless, he went 5-5 with a 3.69 ERA in 39 games this season, 12 of which were starts in place of the struggling Tim Lincecum. At one point, Petit retired 46 consecutive batters, setting a big-league record.
His best work has come in this postseason. He became one of only three relievers to win two games in the same postseason in which at least three scoreless innings were logged in each outing, joining the Yankees' Sparky Lyle (1977) and the Pirates' Bruce Kison (1971).
In nine shutout innings spread over two playoff games, Petit has allowed only two hits.
"No, I don't think you could overstate it,'' Posey said of Petit's impact. "We know how important he's been to our team the whole year. I think some people are starting to get to see it a little bit more now that he's on this stage.''