OAKLAND -- Though the move was essentially made Tuesday night, the A's announced Wednesday that they've optioned rookie righty Jason Windsor to Triple-A Sacramento and recalled lefty Randy Keisler.

Windsor, who was knocked around by the visiting Red Sox for four runs on nine hits over 2 2/3 innings Tuesday, was asked to work on "several things," according to Oakland manager Ken Macha, while back with the River Cats.

In particular, Windsor will need to learn to pick up the pace at which he works.

"He's quite deliberate," Macha said, adding that it causes problems in controlling an opponent's running game.

The A's also would like Windsor to get a better handle on his breaking ball, which was inconsistent in his two starts. Though Windsor allowed one run through five innings of his debut last week in Baltimore, he frequently fell behind in counts and walked the first batter in three innings.

"You've gotta have a swing-and-miss pitch here [in the big leagues]," Macha said. "Otherwise your pitch count is gonna be astronomical."

Macha wasn't without praise for Windsor, though, noting that the 24-year-old's talent gives him a solid base from which to work his way back to Oakland.

"Hopefully," said the skipper, "his next trip up here will be more successful."

This is Keisler's second stint with the A's this year; he was previously with the club from May 12-June 8, posting a 4.50 ERA and a .350 opponents' batting average in 11 relief appearances.

Keisler is 5-3 with a 2.66 ERA and one save in 19 games -- 10 starts -- with Sacramento this year. His past four appearances with the River Cats were starts, and he was 2-0 with a 2.74 ERA over that span, but he'll be used in relief again with the A's.

"He's here as insurance in case something [bad] were to happen early today," Macha said.

Windsor was next scheduled to start for the A's on Sunday, and Macha suggested that righty Kirk Saarloos, who has bounced between the rotation and relief work all year, will get the call.

More Chavez: Third baseman Eric Chavez, whose persistent tendinitis in both forearms remains a mystery to the club's medical personnel, spent part of Wednesday morning in downtown Oakland and didn't arrive at the park until shortly before game time.

Previous MRI exams of Chavez's forearms have shed little light on his problem, so more MRI exams were taken of both elbows Wednesday.

"We're working our way up," said A's athletic trainer Larry Davis. "This was the next logical place to search for the source of his discomfort."

Chavez mentioned to a local reporter Monday that he was looking into acupuncture as a possible remedy, but Davis didn't seem wild about the idea.

"He's mentioned it," Davis conceded, "but it's not something we're actively considering."

Macha said he thought Chavez looked better at the plate Tuesday night than he had in a while, but Chavez entered Wednesday batting .143 (16-for-112) in his previous 30 games and has frequently voiced his frustration over feeling helpless at the plate.

"Your perception that he's down in the dumps is probably because he feels like he's letting a lot of people down," Macha said. "He feels he should be in there helping the team, and he's not doing that. ... But when I see him before the game, there's a bounce in his step, a smile on his face. He still has a positive frame of mind when he comes in here."

Dribblers: Lefty Joe Kennedy, who has been on the disabled list since May 11, reported no pain in his shoulder the day after a bullpen session Tuesday, and he's now out of the trainers' hands and into the hands of pitching coach Curt Young. "It's still gonna be a while," Macha said of Kennedy's return, "because he's been out so long." ... Lefty reliever Scott Sauerbeck, who tweaked his groin during Tuesday's game, said he felt better than he expected to feel Wednesday. He's listed as day-to-day. ... Dan Johnson went 2-for-5 with a double Tuesday and saw his batting average with the River Cats drop. He was batting .475 with four homers, five doubles and 15 RBIs in 10 games heading into Sacramento's night game at Albuquerque on Wednesday.

Coming up: A's righty Joe Blanton (10-8, 4.90 ERA) will take on visiting Blue Jays lefty Ted Lilly (9-8, 3.89 ERA) on Thursday in the opener of a four-game series. The first pitch is set for 7:05 p.m. PT.