This will be Chavez's fifth overall surgery since Sept. 5, 2007, and his second microdiscectomy on his back, this time on a different spot, Geren said.
"This is his best chance to play again. ... It's been tough for him personally," Geren said. "He's a big-time player, Gold Glover that we miss. I still keep the hope and stay positive that he's going to contribute next year."
From 2000 to 2006, Chavez hit at least 22 home runs every season. He drove in 114 runs in 2001, 109 in 2002 and 101 in 2003. He won six consecutive Gold Gloves from 2001-2006.
But in 2007, Chavez began battling injuries. In a 10-week span that year, he underwent three surgeries. He had surgery to repair a torn labrum in his throwing shoulder on Sept. 5 that year, then a microdiscectomy on his back on Oct. 9. Finally, he had surgery on his left shoulder on Nov. 16.
Last year he underwent season-ending surgery on his right shoulder on Aug. 13.
Chavez played only 90 games in 2007, nine in 2008 and eight this season. He went on the 15-day disabled list on May 1, retroactive to April 25, with a strained right forearm. He suffered back spasms on May 10. An MRI detected a bulging disk in his back. On May 19, he was transferred to the 60-day disabled list.
"It's tough," A's second baseman Mark Ellis said. "The guy's gone through a lot, obviously, the last couple years. He hasn't been able to do what he loves to do, play baseball. Everybody in here knows how much he loves to play.
"I feel bad because a lot of guys in the clubhouse don't even realize what Chavy was -- a Gold Glove third baseman who hits 30 home runs a year. I'm one of the few guys that was here when Chavy was really good. Hopefully he's going to be all right. Hopefully he can come back. ... Everybody in here really respects him. We miss him."
Now the question is whether Chavez's teammates will ever get a chance to see him play again.
"He's been a real tough guy throughout it," Geren said. "He's battled real hard. He's had to overcome numerous surgeries. Unfortunately, another setback for him. One thing he does do, he works really hard. He came in in great shape and strong. He rehabbed real hard. You have to give him all the credit for really working hard."
In another development, outfielder Travis Buck was reinstated from the DL (strained left oblique) but optioned to Triple-A Sacramento. Buck is hitting .235 with three home runs in 28 games with the A's. He homered in each of his past two games before going on the DL.
"Kind of sticking with the roster here," Geren said. "[Chris Denorfia] can play all three [outfield positions], and he's right-handed. Just the composition of the roster, I like right now. Keeps Travis playing. He's obviously a talented guy with a bright future in the organization."
Eric Gilmore is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.