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7/21/2014 1:34 P.M. ET

Concussion sends Belt to disabled list

MIAMI -- In addition to dropping the series finale to the Marlins on Sunday, the Giants also lost Brandon Belt to a concussion, as the first baseman was placed on the seven-day disabled list Monday.

The Giants also placed right-hander Matt Cain on the 15-day disabled list Monday with right elbow inflammation. To replace Cain and Belt on the active roster, the club recalled right-hander George Kontos and infielder Adam Duvall from Triple-A Fresno.

Belt's condition was uncertain before the start of play Sunday, but the first baseman hadn't quite recovered from getting hit in the face when he arrived at Marlins Park. He was tested for a concussion shortly after.

Only team doctors checked him out after Saturday's victory over the Marlins. Belt, who was fielding at first during batting practice when the accident occurred, left that game in the third inning with dizziness, a headache and nausea.

Manager Bruce Bochy said it was possible that South Florida humidity triggered Belt's symptoms. He'd been fine and ended up pulling a double into the right-field corner in his first at-bat. Belt, who returned July 4 after missing 50 games with a broken thumb, had gone 4-for-11 over his last four games.

"You have no choice in a concussion situation," Bochy said. "It's a bad break for Brandon, who is coming off the DL. My guess is that running to second and third activated it. He was doing pretty well [before that]."

Arias gets chance to improve numbers vs. lefties

MIAMI -- Shortstop Brandon Crawford was out of the Giants' lineup and Joaquin Arias was in Sunday at Marlins Park -- but manager Bruce Bochy confirmed he was just invoking a routine day-game-after-night-game strategy in order to give Arias a chance against Marlins lefty Brad Hand.

"This isn't a message," he said. "[Crawford is] hitting lefties. The numbers show it."

Entering Sunday, Crawford had lit up southpaws this season with a .322 average, 11 extra-base hits and 14 RBIs in 87 at-bats against them. Arias, however, was only 10-for-54 when facing left-handed pitching. He ended up going 0-for-3 against Hand.

But Bochy believes part of the reason for Arias' struggles has been his lack of playing time.

"I think that's the biggest reason he probably hasn't gotten on track with the bat," Bochy said. "More of his at-bats are against righties and he hasn't gotten consistent at-bats against lefties."

Considering the funk Crawford got into at the end of the first half -- he had just six hits in 38 at-bats to kick off his first 12 games in July -- Bochy has resolved to give his regular shortstop more rest as the season goes on, thus giving Arias a bigger opportunity to improve.

It won't always be Crawford out of the lineup in Arias' place, though. Bochy suggested he could put him in at second base as well.

And with Brandon Belt having to miss more of the season after being diagnosed with a concussion Sunday, it could be that Arias will play more even more often. He's already appeared in 67 games and is batting .182 in 121 at-bats.

Maria Torres is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.