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3/22/2014 1:19 A.M. ET

Hembree among seven sent down to Minors

SCOTTSDALE, Ariz. -- Rookie Heath Hembree, who appeared to have a legitimate chance at claiming a spot in the Giants' season-opening bullpen, was among seven players sent to the Minor Leagues on Friday.

Hembree and fellow right-handed relievers Erik Cordier and Jake Dunning were optioned to Triple-A Fresno. Catcher Guillermo Quiroz, first baseman Mark Minicozzi and right-handers Brett Bochy and Adam Reifer were reassigned to Minor League camp. The Giants have 33 players left in big league camp.

Hembree, who was unscored upon in 7 2/3 innings spanning nine late-season games with the Giants last year, sustained his momentum this spring. He surrendered one earned run and one hit in four innings over five appearances. He recorded an opponents' batting average of .071.

That wasn't enough for the Giants' braintrust, which decided that the 25-year-old Hembree, ranked as the 11th-best prospect in the farm system, needed to sharpen his off-speed pitches.

"For his development, it's best for him and for the organization to go down and continue to pitch," manager Bruce Bochy said.

Bochy expressed a similar mix of praise and counsel regarding Dunning, who posted a 1.42 ERA in six Cactus League games after posting a 2.84 ERA in 29 appearances for the Giants last year.

The moves dramatically shrank the field of candidates remaining for the pair of bullpen vacancies. Right-handers George Kontos, Derek Law, Kameron Loe, Jean Machi and Yusmeiro Petit are in the mix, along with left-handers David Huff and Dan Runzler. Petit, Huff and Loe are being considered for a long-relief role.

"I think it's going to go down to the last couple of days before we know who'll [win] the final two spots," Bochy said.

Demoting his son wasn't an easy task for Bochy, who performed the deed last year while taking Brett to dinner. This time, the Bochys met for breakfast. "It was cheaper," Bruce Bochy jokingly said.

The younger Bochy sported a 2.08 ERA in five appearances. "Brett had a nice camp," Bruce Bochy said. "He didn't get a lot of work, but he held his own."

Minicozzi was the story of camp early in the Cactus League season, having rejoined the Giants in 2012 after four years of overcoming injuries and playing internationally. He hit well initially but tapered off to .216 in 17 games.

"Great story, how he's persevered," Bochy said.

Petit sharp, strengthens case for long-relief role

SCOTTSDALE, Ariz. -- Giants manager Bruce Bochy minced no words in discussing Yusmeiro Petit's performance on Friday night.

"This was a big start for Petit," Bochy said after the right-hander struck out seven in four innings as the Giants blanked Oakland, 3-0. "I think that he came into camp a little behind with his conditioning, as far as pitching."

Petit probably can't afford to stay behind. That's because left-hander David Huff is pushing Petit for the long-relief role. Huff followed Petit with three perfect innings against the A's.

Bochy said that beginning the season with both Petit and Huff on the staff is "a possibility," though the other contenders for at least two apparent bullpen openings -- Dan Runzler, Kameron Loe, Jean Machi, George Kontos and rookie Derek Law -- will strive to make their presence felt in the exhibition season's final week.

For now, Petit would appear to have an edge. The 4-1 record he compiled toward the end of last season strengthens his credentials. He displayed that form against the A's, limiting them to two hits and relying on his curveball to record most of his strikeouts.

Predictably, Petit said that he felt fine and ready to accept any role. "Long relief, starter, whatever they want," said the 29-year-old, who probably would be first in line to join the rotation if injuries or ineffectiveness derailed one of the Giants' incumbent starters.

Cain regains rhythm with Triple-A tuneup

SCOTTSDALE, Ariz. -- Recovering from a stunningly subpar outing, even by Spring Training standards, Giants right-hander Matt Cain continued his regular-season preparation Friday by pitching six innings against the Angels' Triple-A squad in a Minor League exhibition at Tempe, Ariz.

Cain yielded just three hits, including home runs to Brennan Boesch and J.B. Shuck. San Francisco's No. 2 starter said that he managed to establish a rhythm by not forcing his pitching mechanics. Last Saturday, Cain surrendered seven runs in 2 2/3 innings to the A's.

"Today was better. The other day was kind of out of whack," said Cain, who built his stamina by throwing 90 pitches.

Cain will make one more exhibition appearance before facing the Arizona Diamondbacks in the regular season's second game on April 1.

Posey to make start at first before camp breaks

SCOTTSDALE, Ariz. -- Buster Posey, All-Star catcher and backup first baseman, will start a game at the latter spot before the Giants break camp here, manager Bruce Bochy said Friday.

The latest round of roster cuts left Brandon Belt as the only true first baseman in big league camp. Non-roster invitee Mark Minicozzi played a team-high 93 1/3 innings at first base before he was reassigned to Minor League camp Friday.

Thus, Bochy said Posey will receive a start at first, probably before the Giants leave Arizona on Wednesday. Posey started 77 regular-season games at first base since 2010, primarily to keep his bat in the lineup while sparing him from the rigors of catching.

Chris Haft is a reporter for MLB.com. Read his blog, Haft-Baked Ideas, and follow him on Twitter at @sfgiantsbeat. This story was not subject to the approval of Major League Baseball or its clubs.