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4/24/2013 4:22 A.M. ET

Plaque honoring Bonds' 756th HR goes missing

SAN FRANCISCO -- The Giants are planning to replace the marker commemorating Barry Bonds' record-breaking 756th home run that recently disappeared from its spot on the right-center-field wall at AT&T Park.

A San Francisco Chronicle report said that team and ballpark officials plan to scrutinize security video spanning a weeklong period in hopes of finding clues about the apparent theft.

Except for scattered photographs and signs in a right-center field archway denoting the Giants who exceeded 500 career home runs, there's relatively little evidence at the ballpark showing that Bonds, baseball's all-time home run leader with 762, ever played in San Francisco.

His jersey number 25 has not been officially retired, though no player has worn it since he played his final game in 2007. Giants officials have said that Bonds' number won't be removed from circulation until he's elected to baseball's Hall of Fame -- which is an issue in itself, given the cloud of performance-enhancing drug use that hovers over him.

Quiroz finds niche in pinch-hit role for Giants

SAN FRANCISCO -- Guillermo Quiroz has seized the opportunity that playing in the National League has afforded him.

The reserve catcher is 3-for-5 as a pinch-hitter. Performing entirely for American League clubs, who use pinch-hitters less frequently, Quiroz accumulated only six pinch-hit plate appearances from 2004-2012 and went 0-for-5.

Though Quiroz is the only Giants position player not to start a game, he senses that he has at least a chance of coming off the bench, given manager Bruce Bochy's belief in using his entire roster and the flexibility of having three catchers at his disposal.

"I'm starting to feel comfortable now," Quiroz said. "I know I'm probably going to come up sometime in the game. The American League was a lot different."

Some pinch-hitters swing at the first pitch they like. But Quiroz is willing to be patient.

"My ideal plan is to work the count," he said.

Quiroz engineered that kind of at-bat Monday night against Arizona starter Wade Miley, making the left-hander throw seven pitches before lining a 2-2 delivery for a single. His other two pinch-hits came on counts of 2-0 and 0-1, reflecting his ability to adjust.

Opposing pitchers muscling up at plate vs. Giants

SAN FRANCISCO -- When Arizona's Wade Miley homered off Ryan Vogelsong in Monday's fifth inning, the Giants qualified for the dubious-distinction club.

Miley became the third opposing pitcher to go deep against San Francisco, joining Los Angeles' Clayton Kershaw on Opening Day and Milwaukee's Yovani Gallardo last Thursday. According to the Giants' media relations department, the club hadn't yielded homers to three opposing pitchers since June 1953.

Entering Tuesday, only two other Major League pitchers had homered. Giants manager Bruce Bochy defended his pitchers, insisting that they're not regarding their counterparts from other teams lightly.

Bochy pointed out that Miley connected with a 2-0 delivery from Vogelsong.

"If you get down 2-0 on a pitcher, you're going to challenge him," Bochy said.

Gallardo, an accomplished hitter, has 11 career home runs. And Kershaw, who possesses an athletic 6-foot-3, 220-pound physique, was bound to hit one out eventually.

"These guys are hitters," Bochy said. "They're not pitchers trying to get hits."

Chris Haft is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.