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8/26/2014 2:14 A.M. ET

Giants add Kontos to bolster 'pen, option Duvall

SAN FRANCISCO -- After a subpar performance by the bullpen in Sunday's 14-6 loss to the Nationals, the Giants on Monday added a back-end relief arm by recalling right-hander George Kontos. First baseman Adam Duvall was optioned to Triple-A Fresno to make room on the 25-man roster, the team announced.

Kontos is 3-0 with a 3.00 ERA in 14 appearances with the Giants this season. The 29-year-old last appeared in a game with the Giants on July 25.

Duvall has hit .180 with two home runs and three RBIs in 21 games in the Majors this season. The rookie was 1-for-14 (.077) in his last six games.

Giants to skip Lincecum, start Petit instead

SAN FRANCISCO -- Yusmeiro Petit will take over for Tim Lincecum in the Giants' rotation Thursday, manager Bruce Bochy said before Monday night's game.

Bochy said the rotation would be reassessed after Petit's start, so it's unknown when or if Lincecum will return to the rotation.

The move came as little surprise after the Giants alluded to the switch last weekend after Lincecum's latest struggles. In eight appearances (seven starts) since the All-Star break, Lincecum has gone 1-4 with an 8.07 ERA. He's been tagged for 29 earned runs on 46 hits and 18 walks in 32 1/3 innings.

"He's a little off balance," said Bochy, who listed a need for "cleaning up the delivery" as Lincecum's biggest problem right now.

A month and a half ago, Lincecum was one of the Majors' top pitchers, evidenced by a 0.30 ERA in four late June/early July starts. Now, he'll be used as a sixth- or seventh-inning reliever.

"He's all for this; he knows it's probably a good time for this, to back him off a little bit," Bochy said.

The hope is the increased side sessions in the bullpen will help Lincecum regain the balance in his delivery and also boost his confidence, which has once again waned.

In six starts, Petit is 1-2 with a 6.32 ERA. He's fared much better as a reliever, a role in which he's posted a 1.84 ERA in 49 innings. He hasn't allowed a run in his last six appearances, a span of 12 1/3 innings.

Bochy ejected for arguing balls and strikes

SAN FRANCISCO -- Giants manager Bruce Bochy voiced his displeasure with home-plate umpire Doug Eddings' strike zone throughout Monday night's game, and that came to a head in the bottom of the eighth inning.

Buster Posey was called out on a strike three that appeared to be well below the strike zone. Bochy stormed out of the dugout, hat in hand, and kicked dirt in the direction of home plate while lambasting Eddings for the call. The outburst earned Bochy an ejection.

"Obviously I didn't like it, and that's why I wasn't around to watch the rest of the game," Bochy said after the completion of the team's 3-2 loss. "It was a critical pitch, with two strikes and Posey up there. That's a tough way to end that at-bat."

The ejection was Bochy's third this season.

Scutaro won't return to Giants this season

SAN FRANCISCO -- It came as no surprise, but Giants manager Bruce Bochy confirmed Monday that injured second baseman Marco Scutaro's 2014 season is over.

"We don't expect to see Marco again this year," Bochy said of Scutaro, who's back home in Florida, where his back flared up again last week.

After missing the first three months of the season with back problems, Scutaro made a brief return in July. He hit .091 (1-for-11) in five games before the back problems forced him to return to the disabled list.

The emergence of rookie Joe Panik (.400 average, one home run, eight RBIs in August) has converted the position into one of strength for the Giants.

Belt working out, but needs more time in recovery

SAN FRANCISCO -- Giants manager Bruce Bochy said first baseman Brandon Belt will need "a couple more weeks" before returning to the team.

Belt hasn't resumed baseball activities, but is working out again, Bochy said.

In 16 games after returning from a broken thumb in early July, Belt hit .175 with two home runs and six RBIs. He was then concussed July 29 after he was struck by an errant throw from Marco Scutaro during pregame warmups against the Marlins.

He's hitting .237 with 11 home runs and 24 RBIs this season.

In other concussion-related news, catcher Hector Sanchez will be evaluated by specialist Michael Collins in Pittsburgh on Tuesday, so more on his status will be known after.

Ryan Hood is an associate reporter for MLB.com. Follow him on Twitter @ryanhood19. This story was not subject to the approval of Major League Baseball or its clubs.