It's not pain in the third baseman's inflamed right shoulder that has kept him wide-eyed into the early morning hours. Rather, it's the uncertainty surrounding the injury that has left Chavez tossing and turning.
"I've yet to hear definitive answers that have let me sleep well at night," Chavez said before Friday's series opener against the visiting Rangers.
The A's infielder, who has been keeping plenty other teammates company on the disabled list since July 2, had been rehabbing his shoulder in San Diego before Friday's return to Oakland -- where he was hoping to throw and hit off a tee.
"I'm here for a week or two to see if I'm going to come back to play this year or not," Chavez said. "I just gotta wait. I want to wait for a good week and take some ground balls."
Chavez's current stint on the DL is his second of the season and third since July 27, 2007. He played 23 games after starting the year rehabbing from offseason back surgery -- a number most expected to be much higher, considering he underwent three surgeries during a 10-week span in the offseason, including an operation to repair a torn labrum in his right shoulder in September.
"When I first came back this season, the back was a bigger concern more than anything," Chavez said. "The shoulder felt as good as it could."
But throwing -- particularly during games -- is what Chavez believes put him back on the bench.
"I'm 95 percent sure it's just from throwing," Chavez said. "Game throws was what was really bothering me."
Needless to say, the mild games of catch he played with his father while in San Diego didn't hurt -- or help -- the situation.
"I could have thrown to myself," Chavez quippped.
Any hint of a grin, though, faded when asked by a reporter if his injured shoulder meant a possible end to his 10-year Major League career. Once again, Chavez shrugged his shoulders to go along with the theme of uncertainty encompassing his injury.
"There might be some big decisions," Chavez said. "It's hard for me to give an honest answer. All I can do is what the doctors tell me."
The 30-year-old mentioned surgery is not beyond the realm of possibilities, but he'll be the first to say he doesn't expect an operation to fix all.
"To be honest with you, I'm just dealing with a really bad shoulder," Chavez said. "There are a lot of things going on with it. The way my shoulder's been for my career, I don't see it improving."
That message should probably be relayed to manager Bob Geren, who expressed nothing but his usual positive vibes when asked about the third baseman.
"I'm just glad he's here and starting baseball activity," the skipper said. "I'm looking forward to his comeback. ... I'm looking at it in a positive way."
That's what Chavez is attempting to do -- he just can't help but wonder about a realistic future, though.
"I'm not trying to over-exaggerate the situation or underplay it," Chavez said. "I've found myself in the worst predicament possible as a player. I've always taken pride in being out there every day."
Chavez is in the fourth year of a six-year contract extension and has racked up more seasons in Oakland than any other player in A's history besides Rickey Henderson (14), Mark McGwire (12) and Terry Steinbach (11). Whether he can keep climbing those ranks, though, remains in doubt.
"We know what's going on -- it will depend on how I respond when I throw the ball," Chavez said. "If I come back, the rest of the year will be a telling story. It will be the same when I start next season, too.
"I'm not at ease about it. I've had four years where my career has totally been affected by it. It's very frustrating."
Jane Lee is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.