Brown, whose .620 OPS ranks among the lowest for everyday players this season, has less than two months to atone. Sandberg expects to have competition in left next season.
"I would say that it's open right now," he said. "I don't think there is a solid, concrete guy right now as far as that goes. That's why there is some rotation out there. I will give everybody some opportunities. That will continue throughout the rest of the season."
Brown said the surgery on his tonsils could require two weeks of recovery. He said the issue has not bothered him all season, but he does often suffer from a sore throat.
"I think I'm going to be fine," Brown said. "It's just sleeping on my back; every time I sleep on my back with my mouth open, it hits those tonsils. I'm going to avoid that for sure."
No Lee update
The team offered no information about Cliff Lee, who suffered a strained left elbow last week. Sandberg said Lee had not yet undergone an MRI examination, and he could not say when that would happen. Lee met with a team doctor Saturday.
"There wasn't a whole lot revealed from that," Sandberg said.
David Buchanan will be recalled Wednesday to fill Lee's spot in the rotation. Buchanan, 25, was scratched from his scheduled start Tuesday morning at triple-A Lehigh Valley.
The rookie righthander made 10 starts for the Phillies as Lee's substitute earlier this season. He posted a 4.40 ERA and made one of his best starts July 10 at Milwaukee before being demoted.
The final two months are important for Buchanan, one of the few 2015 rotation options the Phillies hold. A decent impression could guarantee him a job next spring.
A reliever - either Cesar Jimenez or Hector Neris - must be cleared to add Buchanan to the roster. . . . Righthander Aaron Nola, the No. 7 overall pick in the June draft, will make his first start at double-A Reading on Wednesday. He was the first player among Major League Baseball's 1,215 draftees to reach double A.