SAN FRANCISCO -- Brandon Hicks has plenty of reasons to smile. He just doesn't necessarily do it for the world to see.

Hicks isn't among the more demonstrative Giants. Angel Pagan often salutes manager Bruce Bochy after taking an extra base. Pablo Sandoval claps his hands in sheer exuberance after rapping a key hit. Even Buster Posey occasionally allows himself a furtive fist pump after homering. Hicks, however, tends to remain expressionless while contributing as much as any Giant, if not more, to the team's success.

"He has a very dry sense of humor," said Hicks' double-play partner, shortstop Brandon Crawford. "But he'll keep his game face on. He is hard to get a read on."

Hicks' gravity was mentioned to Atlanta outfielder Jason Heyward, one of his more accomplished Minor League teammates. Heyward laughed, a reaction Hicks typically avoids in public.

"That's what you know," Heyward said. "He jokes around and has a good time. He's on point when he needs to be on point. But at the same time, you can rely on him to keep the mood light as well."

Hicks admitted that he often seems grim.

"I guess it's just the look on my face," he said recently. "It looks so serious, but I'm really not ever very serious. I like to joke around and have fun. You won't survive in this game if you're serious [all the time]."

Hicks' performance indicates he's maintaining perspective nicely. The 28-year-old has far exceeded any expectations the Giants might have had for him since he made the Opening Day squad as a non-roster invitee to Spring Training. If Hicks' behavior doesn't exude hilarity, his .195 batting average certainly does. It laughs in the face of conventional wisdom, since it conveys nothing about his value to San Francisco as the replacement for injured second baseman Marco Scutaro.

Hicks has been integral to the Giants' increased power and improved defense, essential factors in their rise to first place in the National League West. They'll strive to summon these traits Tuesday when they open a three-game series at second-place Colorado, which happens to trail San Francisco by three games in the division standings.

After hitting three homers during brief stints with Atlanta and Oakland from 2010-12, Hicks has amassed seven for the Giants, helping him compile a .415 slugging percentage. He's also tied for fourth among the Giants with 18 RBIs.

Moreover, each of Hicks' homers bore impact. His most recent roundtripper, a two-run drive off Los Angeles mega-ace Clayton Kershaw on May 11, put the Giants ahead in the seventh inning. Earlier in that series, Hicks tied the score in the seventh inning against Josh Beckett in a game San Francisco proceeded to win in 10 innings. Hicks also delivered a three-run walk-off homer April 27 against Cleveland.

Two of Hicks' homers trimmed a Giants deficit to one run. One accelerated a rally during San Francisco's 12-10, 11-inning win at Colorado on April 23. Another proved essential in a taut April 30 contest against San Diego that the Giants won, 3-2.

Heyward recognized Hicks' offensive potential after the Braves selected them in the first and third rounds, respectively, in the 2007 First-Year Player Draft.

"I've known he had power since I played with him," said Heyward, who finished second to Posey in the 2010 NL Rookie of the Year Award voting. "He's a guy who wants to be in big situations."

Hicks has supplemented his production by drawing 20 walks, second on the club to Posey's 21. This has partially offset Hicks' primary offensive flaw: lack of contact. He has struck out 41 times in 142 plate appearances.

"I'm not all that big on batting average," Bochy said. "That's way overrated. It's on-base percentage and slugging. Sometimes you want to give up a little bit to do some damage. That's [Hicks'] style."

Contemporary metrics reflect Hicks' value. According to baseball-reference.com, he has compiled a 1.2 WAR, or wins above replacement. The figure denotes the number of victories an individual would add beyond those that could be provided by a "replacement player" -- that is, a borderline Major Leaguer, which happens to be the profile Hicks has fit through much of his eight-year professional career. Pagan (1.5) and Posey (1.3) are the only Giants whose WAR has exceeded Hicks'.

Additionally, Hicks is tied with Posey with an 8 RAA -- runs above what a league-average player would generate. They're second to Pagan's 10 among all Giants.

Hicks has made an equally enduring impression defensively. Though he was prone to botching routine plays earlier in the season, he has played error-free in his past 27 games. Giants bench coach Ron Wotus, a former infielder who has spent 36 years in professional baseball, said that Hicks turns double plays, particularly when enemy baserunners are bearing down on him at second base, "as well as anybody I've seen."

Heyward explained Hicks' toughness in simple terms.

"He's a baseball player," Heyward said. "He's an old-fashioned baseball player. He wants to do things the right way, wants to hustle and play hard. He enjoys the competition."

Hicks has helped the Giants become more prolific at recording double plays. They entered Monday with 48, third in the NL. Last year, San Francisco ranked next-to-last in the NL with 128 double plays. Hicks' physical gifts, which include a powerful throwing arm, have bolstered the Giants' efficiency.

"Really, what stands out the most about him -- no offense to Marco, because he's a little bit older -- is his athleticism," Crawford said. "He's quick and he has good range. It's fun to work with a guy like that."

Befitting a player whose status was nearly anonymous before the season began, Hicks continues to take nothing for granted. Though he has virtually entrenched himself as San Francisco's everyday second baseman, he won't allow complacency to invade his mindset.

"I still check it out every day," Hicks said, referring to the posted lineup.

This attitude comes naturally for Hicks.

"He's always worked hard," Heyward said. "He's a player who wants to contribute to the team, any way he can -- defensively, offensively. I'm happy to see his hard work paying off."