Sergio Romo closed out Game 2 in the World Series, but he was also lights out down the stretch of the regular season for the Giants. (Marcio Jose Sanchez/ASSOCIATED PRESS)

Coming into this season, Sergio Romo had appeared in 207 major league games with San Francisco and had all of three saves. He was a setup man in what had been an effective Giants bullpen, but nothing more.

When Giants closer Brian Wilson went down with elbow problems in April, though, Manager Bruce Bochy had to figure out how to make up for the loss of the man who had come to represent the eccentric personality of his team.

“I just love pitching, man,” Romo said. “I love getting the ball, and I love helping this team win games.”

That, essentially, is what Bochy learned about Romo even before he made him the Giants’ closer in the second half of the season. Bochy initially chose Santiago Casilla, and the veteran saved his 20th game on June 22. But he then went into a month-long funk, posting a 7.84 ERA and blowing five saves in his next 13 appearances.

Enter Romo. From August through the end of the season, he posted nine of his 14 saves and rang up a 1.13 ERA with 27 strikeouts and one walk in 24 innings. Now entrenched as the closer, Romo saved Saturday night’s 2-0 victory against Detroit in Game 3 of the World Series with a perfect ninth inning. He has now allowed only one run in 92 / 3 innings in the postseason.

“I think more than anything, what I’ve learned is how much he cares about his teammates, and that’s how he pitches,” Bochy said. “He wants to win for them and the club. Very unselfish player.”

Over the past two seasons — as a setup man and a closer — Romo has become one of the most effective relievers in the game, striking out 133 men in 1031 / 3 innings while walking just 15.

Giants’ DH goes hitless

Bochy inserted backup catcher Hector Sanchez as the designated hitter for the first game played under American League rules. Sanchez, a switch-hitter, had never faced Detroit starter Anibal Sanchez (no relation), but he was the easy choice over veteran Aubrey Huff. Huff, a left-handed hitter, was 0 for 12 with a walk and three strikeouts against Anibal Sanchez in his career.

“I just remember so many clutch hits that Hector has given us,” Bochy said. “So I just felt like he’s earned this.”

Hector Sanchez, though, went 0 for 4 with three strikeouts. Delmon Young, the Tigers’ regular designated hitter, returned to that spot and went 0 for 3 with a walk. . . .

Detroit’s starter for Game 4, right-hander Max Scherzer, has allowed just eight base runners — five hits and three walks — in his two postseason starts thus far. That continues a strong stretch that began in August. After starting the season 10-8 with a 4.72 ERA, Scherzer has been dominant in his last dozen starts: 7-1 with a 1.52 ERA with 89 strikeouts and just 17 walks.