When Brian Wilson threw a slider past Texas’ Nelson Cruz to end the 2010 World Series, the Giants’ closer turned around, crossed his arms and pointed upward with his right index finger.

When Sergio Romo froze Detroit’s Miguel Cabrera with a fastball, ending the 2012 World Series, he shouted to the skies, gyrated and hopped up and down while pounding his fist into his glove.

Those were their routines. They were expected and welcomed. That’s who they are.

Santiago Casilla’s shtick? Doesn’t have one. Doesn’t want one. Doesn’t even consider himself a closer. Just a guy who gets the ninth-inning call. After saves, sometimes he offers his catcher a handshake. Sometimes he doesn’t.

No outgoing personality. No hairy fashion statement. No idiosyncrasy. No flash.

An anti-closer.

“Half the time after games, I have to yell at Casilla to come shake my hand,” Buster Posey said before Wednesday’s workout at China Basin, “because he’s running off to congratulate the fielder for making the play.”

Casilla, 34, could be the Giants’ third World Series closer in five years, but he comes without a multitiered on-field production or even his own entry music — the song he wanted, the Giants deemed too tame. He’s far more low-key than his predecessors, keeping his emotions to himself no matter how big the stage.

Make no mistake. Casilla does his thing with less hullabaloo than the others, but he’s every bit as competitive, energetic and determined to help the Giants win another championship.

“He’s a special guy,” reliever Javier Lopez said. “He’s got a different style, no doubt about it. There’s nothing he really does that’s super crazy. I’ve seen a couple of fist pumps out of him after a big out, but honestly, that’s about it. He keeps to himself and remains poised, and I feel that’s a great attribute to have, especially when asked to pitch in pretty key spots.”

At midseason, Casilla took over the closer’s role from Romo, who was struggling, and he finished the season with a 1.70 ERA (0.79 on the road) in 54 appearances, earning 19 saves in 23 opportunities. He pitched three of four games in the Division Series and earned two saves, including Tuesday’s clincher, his 13th straight scoreless postseason outing.

He retired three of four batters, feeling perfectly comfortable with issuing a two-out walk to Bryce Harper, who homered three times in the series.

“Go over and hang out at first,” quipped Casilla, who retired Wilson Ramos for the final out.

With the A’s, Casilla was known as Jairo Garcia and had a 5.96 ERA in 2009, after which his career turned when he mastered a curve in winter ball, taught to him by a teammate in the Dominican Republic. He said once he learned the grip, he gained instant success. The Giants signed him for 2010, and his ERA in five seasons is 2.10.

“He probably doesn’t get nearly the credit he deserves,” Posey said.

It would help if he’d promote himself, which Casilla has no interest in. Romo enters games to “El Mechón,” a Mexican corrido that has fans dancing in the aisles. Wilson entered to “Jump Around,” Robb Nen to “Smoke on the Water.”

When Casilla, a man of faith, was asked what he wanted, he picked a religious song in Spanish. The marketing department, in the business of setting the right mood for the crowd, didn’t consider it upbeat enough.

“They wanted something with more emotion for the people,” said Casilla, who accepts whatever’s played. That’s him. No fuss, no muss. But plenty of heart.

Asked why he doesn’t show much on-field emotion, Casilla said, “I don’t want to show emotion, but I have it in me. I have a lot of emotion. I try to control my energy.”

He has a lot of confidence, too. During a Wednesday interview, Casilla — showing a much improved grasp of the English language than a year ago — asked a reporter, “Do you believe the Giants will win? ... I believe we will win the World Series. The people we have here. They want to win. They believe.”

They believe in Casilla. Except when he starts talking about his changeup. Unlike Wilson and Romo, Casilla has a big repertoire of pitches, starting with a 94-mph fastball, and he’ll list them all, including the change.

“His sinker sets up all the other pitches,” Lopez said. “I think that’s his best pitch. He’ll tell you it’s his changeup.”

Posey, loud enough for Casilla to hear, said, “He doesn’t have a changeup. Don’t let him tell you he has a changeup.”

Said Casilla: “I don’t use it much. Just sometimes.”

Probably not in the National League Championship Series, which opens Saturday in St. Louis. He has enough other pitches to get by, even if the presentation is under the radar.

John Shea is a San Francisco Chronicle staff writer. E-mail: jshea@sfchronicle.com. Twitter @JohnSheaHey.