The team announced that Bradley was suffering from "soreness in his right side." Asked if it was a strained oblique muscle, an injury that can sideline a player for several days and even weeks, Geren said, "I don't think so. I hope not."
"I'd just say he's day-to-day," the skipper continued. "He could play if he had to, but I talked to him after he hit and we agreed it's better to just take a day [off] now and let it settle down a little."
Bradley, who is 6-for-16 (.375) this season, was unavailable for comment before the game.
Before BP, Geren had spoken of his desire to get Todd Walker his first playing time of the year at some point during the series, perhaps by giving Bradley a day off. Scratching Bradley enabled him to do just that, starting Walker at first base and moving Nick Swisher into center field.
"Nick's going to be out there in center whenever Milton needs a day off, anyway," Geren said, "so it'll be good for him to get out there this early in the year."
The lineup Geren posted before BP featured Ellis, who batted ninth in each of the first four games and entered Friday's action with eight RBIs, batting sixth. He was moved up to fifth when Bradley was scratched.
Left fielder Shannon Stewart was in the leadoff spot -- Kendall, who is 2-for-20, led off in each of the first four games -- and Swisher (5-for-12, .417) was in the No. 2 spot for the first time this season.
"I like Nick in the No. 2 spot," Geren said. "I like Nick in a lot of spots, actually. ... Batting second, to me, is [for guys with] a high on-base percentage, and it gives you the opportunity to maybe get him that fifth or sixth at-bat in some games."
Through the first four games, Swisher had drawn a team-high six walks and had an OBP of .611.
As a result of Bradley's absence, designated hitter Mike Piazza moved from cleanup to third in the batting order, and Eric Chavez was bumped up from fifth to fourth. Walker, signed right before the end of Spring Training, batted sixth.
Adam Melhuse, who caught lefty Joe Kennedy on a fairly regular basis this spring, was teamed with Kennedy again Friday and batted ninth. Kendall, who typically hates taking a day off, didn't fight Geren's decision.
"He told me last night," Kendall said. "As long as there's good communication, and there always is with Bob, I'm fine."
Melhuse appreciated the early head's-up, too.
"Most of the time last year, I didn't know I was playing until I got to the park and checked the lineup card," he said. "But Bob told me in the seventh or eighth inning last night. It might not sound like a big deal, but it really does help your preparation."
Eager to chip in: Lefty Lenny DiNardo, who entered Spring Training as a longshot candidate for the No. 5 spot in the rotation but ended up making the team as a reliever in the wake of starter Esteban Loaiza's injury, was the only A's pitcher who didn't appear in any of the team's first four games.
Given that DiNardo is essentially Oakland's designated long man, that's a good thing.
"A guy like me, I'm probably only going to pitch when the starter gets roughed up," he said. "But if our starters are going six, seven innings every night, I'm more than happy to stay in the bullpen."
DiNardo said that when he was with the Red Sox in 2004 and 2005, fellow relievers Mike Timlin, Keith Foulke and current teammate Alan Embree helped teach him how to stay sharp without regular work.
"The veterans took care of me," he said. "It's just knowing your body. If I'm not out there for three days in a row, I know I have to throw in the bullpen on that fourth day."
Minor Leaguer suspended: The Office of the Commissioner on Friday announced that Leonard Landeros, a lefty reliever drafted by the A's in the 29th round of the 2001 First-Year Player Draft, has been suspended for 50 games "for testing positive of a drug of abuse in violation of the Minor League Drug and Prevention Program.
No further details were released, and Oakland's director of player development Keith Lieppman said by phone that he's been instructed to refuse comment about the suspension "due to the complexities of the program."
Landeros, signed out of California's College of the Sequoias, last season was limited by shoulder trouble to 15 games at Class A Stockton, where he went 1-1 with a 3.31 ERA while striking out 15 in 16 1/3 innings.
"He's had quite a few health issues off and on over the years, elbow and shoulder, but he's someone we've always thought could be real good as a situational left-hander," Lieppman said. "His numbers against lefties have been excellent, and he's someone we've though who could -- if he stayed healthy -- move through the system and do well in that role for us."
Dribblers: The primary diversion in the clubhouse before batting practice on Thursday and Friday was watching the Masters golf tournament, for which the players and other team personnel have a nobody-can-pick-Tiger Woods pool. Dan Haren led after the first round. ... Many of the A's say utility infielder Marco Scutaro is the funniest player on the team, but rarely does he flash his humorous side in front of reporters. He made an exception on Friday, launching into a dead-on impression of Piazza's pre-pitch routine -- complete with an emphatic slam of the bat, a fairly pained facial expression and a quick, late look back at the catcher -- that drew laughs from everyone, including Piazza. ... The two big lockers in the far-right corner of the visiting clubhouse at Angel Stadium of Anaheim were reserved for Barry Zito during the final four or five years of his A's career. Now the area is Rich Harden's territory, and he digs it, but he'd rather get a better spot in the extremely cramped clubhouse at Fenway Park. "I always get stuck in the corner," he said. "Every year I move, like, one locker closer to the middle of the row. Maybe they'll give me Zito's spot there now, too. He always had plenty of room." ... First baseman Daric Barton homered and singled, and second baseman Kevin Melillo went 2-for-3 with three walks on Thursday as Triple-A Sacramento beat visiting Tacoma, 8-7, in the season opener for both teams. Righty Jason Windsor allowed four runs over six innings for the win.
Up next: Haren (0-1, 0.00 ERA) will get the ball on Saturday evening opposite righty John Lackey (1-0, 0.00) of the Halos in the third game of the four-game series. The first pitch is scheduled for 6:05 p.m. PT.
Mychael Urban is a national writer for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.