Jones, 37, hit a career-best .364 last year, his third straight season over .320. But he has fallen to .269 this year and is hitting only .229 since June 9, when his average peaked at .335.
The three-month slump is a startling development for the career .308 hitter. He signed a three-year, $42 million contract extension in March that runs through 2012, but says he may retire if he can't reclaim his hitting stroke in 2010.
"If I back up this year with the same kind of year next year, I don't want to play the game," Jones told The Associated Press. "The game is not fun to me when I'm not playing up to my standards.
"I just feel like there are other things I'd rather be doing. Family has a lot do to with it. My boys are getting big enough now, my two littlest ones are going to be starting ball and grade school. I just feel like I want to be there for all that."
He has reached 500 at-bats only once in his last six seasons, due to a long list of injuries. There have been more physical problems in 2009. He has missed the past three starts with a strained oblique muscle and lower back pain.
He grimaced in obvious pain when striking out as a pinch-hitter in the eighth inning of Wednesday night's 6-5 win over the New York Mets.
Nagging injuries have been a constant frustration, but Jones blames his 2009 decline on poor mechanics.
"I don't feel that I've been banged up enough to be performing like this," he said before Wednesday night's game. "I've played more games than I have the past few years and I just haven't been able to find it. That's why I left the door open when I said I'm going to go home this offseason and bust my can to try and get back and have a good season next year."
He says he knows something is wrong with his mechanics just by watching the spin on the ball as it comes off the bat.
"I can tell when I'm swinging the bat good," he said. "There's backspin when I'm swinging the bat good. I'm not hitting doubles, I'm not hitting balls into the gap, I'm not driving the ball out of the ballpark. And even balls that I'm staying inside of and going the other way, there's topspin. That tells me there's something mechanically wrong."
Jones first told The Atlanta Journal-Constitution last week he might retire after the 2010 season.
Braves manager Bobby Cox also is answering questions about retirement.
Cox, 68, says he has not made a commitment to managing in 2010. He said that's the same approach he has taken into every recent offseason.
"Every year it's the same. Nothing has changed," Cox said Wednesday. "Let's just play this season first."
The 2010 season would be Cox's 25th as Atlanta's manager, including his first stint from 1979 to 1981.
Cox has leaned on Jones, the 1999 NL MVP, through most of his current reign as manager, which began in 1990.
Jones ranks among the baseball's top switch-hitters. His 424 career homers rank third all-time for switch-hitters, trailing Mickey Mantle (536) and Eddie Murray (504). His career batting average is second to Frankie Frisch's .316 mark.
Jones has only 16 homers, 64 RBIs and a career-low .435 slugging percentage this season. But he says he believes he is physically capable of delivering the power he showed in 2007, when he hit 29 homers with 102 RBIs.
"Every time I walk to the plate I feel like I can dominate a game with my bat if I'm right," he said. "I've never struggled for three months."
Thanks to the improved balance in the lineup, the Braves are 14-11 in games Jones has not started. They brought a season-best six-game winning streak into Thursday night's game against the Mets and were a season-high nine games over .500, still clinging to faint wild-card hopes.
"We're playing good; the guys are stepping up, swinging the bats, playing good defense," Jones said. "They can hold the fort."