The A's placed pitchers Dallas Braden and Joey Devine on the 15-day disabled list Tuesday, retroactive to March 24.
Pitching coach Curt Young made the decision that Braden would not join the team in Japan on March 15, saying it would be too difficult for Braden to get in his regular work.
REWIND: Braden to miss Japan trip
Braden, 28, continues to rehab his shoulder after undergoing season-ending surgery to repair a torn capsule last May. He made just three starts prior to the injury, going 1-1.
"What I need to do," Braden told the San Francisco Chronicle, "is get myself ready to pitch without any potential conflicts in my workout schedule."
Braden who authored MLB's 19th perfect game on Mother's Day of 2010, will try to regain his 2010 durability; he started 30 games for the A's, going 11-14 with a 3.50 ERA.
Devine, 28, hits the DL with right biceps tendinitis. In 2011, he appeared in 26 games, going 1-1 with a 3.52 ERA.
Devine and Braden will be eligible to come off the disabled list prior to the A's three-game home series against the Royals beginning April 9.
The A's are in a unique situation with spring training games to play after their opening series. They are required to reduce their roster to 25 players by April 4, but are not allowed to carry more than 25 players for the Japan series. As a result, pitchers Tyson Ross and Tommy Milone and first baseman Daric Barton will be inactive for the Japan series, getting the A's roster to 25 active players.