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6/15/2014 10:44 P.M. ET

Back trouble forces Pagan out of Giants' lineup

SAN FRANCISCO -- Giants center fielder Angel Pagan was scratched from Sunday's starting lineup due to lower back stiffness. Manager Bruce Bochy is hopeful the irritation won't cause Pagan to miss any other games.

Bochy said Pagan couldn't swing a bat before Sunday's 8-7 loss to the Rockies. Pagan told Bochy he first felt the discomfort running from first to third in Saturday's game.

Gregor Blanco, originally slated to play left field, was moved to leadoff and center field, while Tyler Colvin took over for Blanco in left.

The scratch made Sunday the third consecutive unfortunate day for Pagan.

Pagan badly misjudged a ball off the bat of Colorado's Brandon Barnes in the ninth inning Saturday, allowing for Barnes' game-winning inside-the-park home run. The previous night, Pagan wrongly threw to third base after catching a fly ball in a double-tag situation, allowing the tying run to advance to second, setting the table for the Giants' demise.

Pagan is hitting .307 with three home runs and 19 RBIs this season, serving as the catalyst for the Giants' offense from the leadoff spot.

Posey feels 'fine' after taking foul tip to mask

SAN FRANCISCO -- It appears the Giants' Sunday afternoon won't regress from bad to worse.

Catcher Buster Posey, removed from Sunday's 8-7 loss to the Rockies in the fourth inning after taking a hard foul tip to the mask, doesn't anticipate missing any playing time.

"I feel fine. It just kind of stung me a little bit. I feel normal," said Posey, who thinks he "probably" will be available to play Tuesday.

Posey was filling up his bat bag at his locker after the game; he expects to be joining his teammates on their upcoming road trip, which starts with a two-game series vs. the White Sox.

Posey remained in the game for the top half of the fourth, but manager Bruce Bochy said Posey was dealing with headaches after returning to the dugout, so his day was over. Posey said after the game that the headaches had dissipated and that he underwent a battery of tests that came back concussion-free.

A concussion would be Posey's first in the big leagues and second of his life; he said he was concussed after being hit in the head by a pitch while playing for Class A Advanced San Jose.

Posey also took a hard foul off the mask in Tuesday's game vs. the Nationals, but he didn't think there was any carryover effect from that blow.

Recently recovered from back irritation, Posey is hitting .271 with nine home runs and 32 RBIs on the season.

Casilla ready to return to Giants' bullpen

SAN FRANCISCO -- Reliever Santiago Casilla threw a second successful rehab outing for Class A Advanced San Jose on Saturday and will rejoin the Giants for the team's upcoming series against the White Sox, manager Bruce Bochy said Sunday.

"He's all set, and that's good news because when it [the injury] happened, we thought this would be longer than what it has been," Bochy said.

To create room on the active roster, the Giants optioned reliever George Kontos to Triple-A Fresno. Kontos was 1-0 with a 3.07 ERA in 11 appearances with the Giants.

"Not sure we'll need the extra pitcher with the day off plus we'll be going with the [designated hitter] so you don't use as many pitchers when you use the DH," Bochy said before Sunday's game.

Casilla's return gives Bochy a good problem to have, creating a bit of a logjam in the bullpen, with non-closer right-handers Casilla, Juan Gutierrez and Jean Machi all having strong seasons in addition to lefty Javier Lopez.

Casilla will return to his role as setup man, bouncing Machi -- owner of a ridiculous 0.29 ERA through 31 innings pitched this season -- back to more of a sixth- and seventh-inning role.

The Giants have off-days Monday and Thursday, sandwiching a two-game series against the American League's White Sox on Tuesday and Wednesday.

Casilla owns a 1.37 ERA through 26 1/3 innings. He strained his right hamstring on May 21.

Bochy ejected near end of frustrating game

SAN FRANCISCO -- A third consecutive disappointing day at the ballpark ended prematurely for Giants manager Bruce Bochy, who was ejected for arguing balls and strikes in the ninth inning by home-plate umpire Mike Muchlinski on Sunday afternoon.

Bochy argued a called third strike that rung up Juan Perez and moved the Giants one out away from succumbing to an 8-7 loss and the Rockies' three-game sweep.

"I'm not concerned," Bochy said when asked about his team losing six of its last seven games. "You're going to have these tough times during the season. What's important is how we deal with it and I was proud of how the guys came out and played."

Romo gets rest in Giants' finale vs. Rockies

SAN FRANCISCO -- After blowing a save opportunity Friday night, Giants closer Sergio Romo said in the clubhouse that he "couldn't wait" to get a chance at redemption. He got that chance Saturday afternoon, and the same lackluster result ensued. This time, he'll have to wait a little longer to again try to redeem himself.

Manager Bruce Bochy said prior to Sunday's game vs. the Rockies that Romo would be unavailable after pitching three consecutive days. The Giants used Juan Gutierrez and Javier Lopez in the eighth inning, and they combined to give up four runs and the lead in an eventual 8-7 loss. Jean Machi pitched the ninth.

"He's tough enough to handle this and deal with this -- only reason he's off today is because he's thrown three days in a row," Bochy said of Romo.

That's just a one-day occurrence, Bochy said. The closer job is Romo's. Bochy planned to meet with Romo in his office after batting practice to discuss his closer's recent outings.

Bochy and Romo have each chalked up the weekend's shortcomings to a bout of bad luck. For the most part, they've liked the pitches he's thrown. A combination of unfortunate hops and defensive lapses has helped contribute to the late-game issues.

"I'm just in disbelief, really, especially the way it went down," Romo said following Saturday's collapse, in which he allowed a two-run, inside-the-park home run to put the Rockies ahead in the ninth.

Searching for an explanation, Romo attributed the Giants' unraveling to the fickle nature of the sport they play.

"That's baseball," he then repeated.

"You look at his outings, some of those pitches aren't too bad," Bochy said Sunday. "He's had some bad luck and that's what you're going to have.

"It's just the way this game goes sometimes."

Romo has blown four saves this season. Three of them have come against the Rockies.

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.